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ANIMAL INTELLIGENCE

THE MACMILLAN COMPANY
NEW YORK + BOSTON - CHICAGO
SAN FRANCISCO

MACMILLAN & CO., LimiTEp

LONDON + BOMBAY - CALCUTTA
MELBOURNE ;

THE MACMILLAN CO. OF CANADA, Lp.
TORONTO

ee

4

ANIMAL INTELLIGENCE

EXPERIMENTAL STUDIES

BY

EDWARD L. THORNDIKE

TEACHERS COLLEGE, COLUMBIA UNIVERSITY

Nef Bork
THE MACMILLAN COMPANY
IQII

Adi rights reserved

CoryRIGHT, 1911,

By THE MACMILLAN COMPANY.

Set up and electrotyped. Published June, rgrr.

177 0

Nortoood ¥ress
J. 8. Cushing Co. — Berwick & Smith Co.
Norwood, Mass., U.S.A.

PREPACE

THE main purpose of this volume is to make accessible
to students of psychology and biology the author’s experi-
mental studies of animal intellect and behavior.1 These
studies have, I am informed by teachers of comparative
psychology, a twofold interest. Since they represent the
first deliberate and extended application of the experi-
mental method in animal psychology, they are a useful
introduction to the later literature of that subject. They
mark the change from books of general argumentation
on the basis of common experience interpreted in terms
of the faculty psychology, to monographs reporting de-
tailed and often highly technical experiments interpreted
in terms of original and acquired connections between
situation and response. Since they represent the point
of view and the method of present animal psychology, but
in the case of very general and simple problems, they are
useful also as readings for students who need a general
acquaintance with some sample of experimental work in
this field.

1“ Animal Intelligence: An Experimental Study of the Associative Pro-
cesses in Animals’ (’98), ‘The Instinctive Reactions of Young Chicks’ (’99),
‘A Note on the Psychology of Fishes’ (’99),and ‘The Mental Life of the
Monkeys’ (’o1). I have added a theoretical paper, ‘The Evolution of the
Human Intellect,’ which appeared in the Popular Science Monthly in 1901,
and which was a direct outgrowth of the experimental work. I am indebted
to the management of the Psychological Review, and that of the American
Naturalist and Popular Science Monthly, for permission to reprint the three
shorter papers.

Vv

vi Preface

It has seemed best to leave the texts unaltered except
for the correction of typographical errors, renumbering
of tables and figures, and redrawing the latter. In a
few places, where the original text has been found likely
to be misunderstood, brief notes have been added. It is
hard to resist the impulse to temper the style, especially
of the ‘ Animal Intelligence,’ with a certain sobriety and
restraint. What one writes at the age of twenty-three
is likely to irritate oneself a dozen years later, as it doubt-
less irritated others at the time. The charitable reader
may allay his irritation by the thought that a degree of
exuberance, even of arrogance, is proper to youth.

To the reports of experimental studies are added two
new essays dealing with the general laws of human and
animal learning.

JANUARY, IQII.

CONTENTS

PAGE

THE STUDY OF CONSCIOUSNESS AND THE STUDY OF BEHAVIOR I
ANIMAL INTELLIGENCE ; : : : : ; ‘ +30 320
Introduction : : ‘ : ; : ap) 2
Description of Ades : ‘ . : 4 . Nee
Experiments with Cats . : : : : : . aes
JOveste tet a c10 0 1 Jit ae a a me Om UN ai eae BC
Experiments with Chicks . : : ; - t £6 NOE
Reasoning or Inference : : : : : . Bi 7
Imitation . ; : ‘ d : : : : Bae Ss

in Chieks:),)°. R < . 5 : : : hee

In Cats . ; ‘ , ; ; : : : Bae =

In Dogs ‘ - : : - : E 2) Gz

The Mental Fact in eS ae ; ‘ . 98
Association by Similarity and the Formation st Condenes 826
Criticism of Previous Theories. : : : : « (Boe
Delicacy of Association : : : ; d , RW 2,
Complexity of Associations . : : ; : : ME
Number of Associations : . i : : : Pra
Permanence of Associations . : ‘ } : , she kee
Inhibition of Instincts by Habit . : : : ; Rg 2. =
Attention . , 3 : : Papas.
The Social eeicic of Ail é : E g 1), PAO
Interaction . : : : ‘ > Ag
Applications to Pedagoey, Anthropolog y, etc. Zé ! - |) 149
Conclusion . : ; : : ‘ Be 5:
THE INSTINCTIVE REACTIONS OF YOUNG CHICKS . ‘ eae 1,
A NOTE ON THE PSYCHOLOGY OF FISHES : : : Ame Gel®)
THE MENTAL LIFE OF THE MONKEYS . : : CAE? iy
Introduction ; : : : : ; : : avid
Apparatus . é : ; : é . : ; BAN 5 |

vii

Vill Contents

Learning without Tuition . ; - :
Tests with Mechanisms .
Tests with Signals
Experiments on the Influence of THtion
Introduction .
Imitation of Human Baines
Imitation of Other Monkeys .
Learning apart from Motor Impulses
General Mental Development of the Monkeys

LAWS AND HYPOTHESES OF BEHAVIOR

THE EVOLUTION OF THE HUMAN INTELLECT

PAGE
182
184
195
209
209
211
219
222,
236

241

282

ANIMAL INTELLIGENCE

CHAPTER I

THE StupyY OF CONSCIOUSNESS AND THE STUDY OF
BEHAVIOR

THE statements about human nature made by psycholo-
gists are of two sorts, — statements about consciousness,
about the inner life of thought and feeling, the ‘self as
conscious,’ the ‘stream of thought’; and statements about
behavior, about the life of man that is left unexplained
by physics, chemistry, anatomy and physiology, and is
roughly compassed for common sense by the terms ‘in-
tellect’ and ‘character.’

Animal psychology shows the same double content.
Some statements concern the conscious states of the animal,
what he is to himself as an inner life; others concern his
original and acquired ways of response, his behavior, what
he is to an outside observer.

Of the psychological terms in common use, some refer
only to conscious states, and some refer to behavior regard-
less of the consciousness accompanying it; but the majority
are ambiguous, referring to the man or animal in question,
at times in his aspect of inner life, at times in his aspect of
reacting organism, and at times as an undefined total
nature. Thus ‘intensity,’ ‘duration’ and ‘quality’ of
sensations, ‘transitive’ and ‘substantive’ states and ‘im-
agery’ almost inevitably refer to states of conscious-

B I

S42 Animal Intelligence

ness. ‘Imitation,’ ‘invention’ and ‘practice’ almost
inevitably refer to behavior observed from the outside.
‘Perception,’ ‘attention,’ ‘memory,’ ‘abstraction,’ ‘rea-
soning’ and ‘will’ are samples of the many terms which
illustrate both ways of studying human and animal
minds. That an animal perceives an object, say, the sun,
may mean either that his mental stream includes an aware-
ness of that object distinguished from the rest of the visual
field; or that he reacts to that object as a unit. ‘Atten-
tion’ may mean a clearness, focalness, of the mental state;
or an exclusiveness and devotion of the total behavior. It
may, that is, be illustrated by the sharpness of objects
illumined by a shaft of light, or by the behavior of a cat
toward the bird it stalks. ‘Memory’ may be conscious-
ness of certain objects, events or facts; or may be the per-
manence of certain tendencies in either thought or action.
‘To recognize’ may be to feel a certain familiarity and
surety of being able to progress to certain judgments about
the thing recognized; or may be to respond to it in cer-
tain accustomed and appropriate ways. ‘Abstraction’ may
refer to ideas of qualities apart from any consciousness of
their concrete accompaniments, and to the power of having
such ideas; or to responses to qualities irrespective of their
concrete accompaniments, and to the power of making such
responses. ‘Reasoning’ may be said to be present when
certain sorts of consciousness, or when certain sorts of
behavior, are present. An account of ‘the will’ is an
account of consciousness as related to action or an account
of the actions themselves. ;

Not only in psychological judgments and psychological
terms, but also in the work of individual psychologists,
this twofold content is seen. Amongst writers in this
country, for example, Titchener has busied himself almost

The Study of Consciousness and Behavior 3

exclusively with consciousness ‘as such’; Stanley Hall,
with behavior; and James, with both. In England Stout,
Galton and Lloyd Morgan have represented the same divi-
sion and union of interests.

On the whole, the psychological work of the last quarter
of the nineteenth century emphasized the study of conscious-
ness to the neglect of the total life of intellect and character.
There was a tendency to an unwise, if not bigoted, attempt
to make the science of human nature synonymous with the
science of facts revealed by introspection. It was, for
example, pretended that the only value of all the measure-
ments of reaction-times was as a means to insight into the
reaction-consciousness, — that the measurements of the
amount of objective difference in the length, brightness or
weight of two objects that men could judge with an assigned
degree of correctness were of value only so far as they
allowed one to infer something about the difference between
two corresponding consciousnesses. It was affirmed that
experimental methods were not to aid the experimenter to
know what the subject did, but to aid the subject to know
what he experienced.

The restriction of studies of human intellect and character
to studies of conscious states was not without influence on
scientific studies of animal psychology. For one thing, it
probably delayed them. So long as introspection was
lauded as the chief method of psychology, a psychologist
would tend to expect too little from mere studies, from the
outside, of creatures who could not report their inner expe-
riences to him in the manner to which he was accustomed.
In the literature of the time will be found many comments
on the extreme difficulty of studying the psychology of
animals and children. But difficulty exists only in the
case of their consciousness. Their behavior, by its simpler

4 Animal Intelligence

nature and causation, is often far easier to study than that
of adults. Again, much time was spent in argumentation
about the criteria of consciousness, that is, about what cer-
tain common facts of behavior meant in reference to inner
experience. The problems of inference about consciousness
from behavior distracted attention from the problems of
learning more about behavior itself. Finally, when psy-
chologists began to observe and experiment upon animal
behavior, they tended to overestimate the resulting insight
into the stream of the animal’s thought and to neglect
the direct facts about what he did and how he did it.

Such observations and experiments are, however, them-
selves a means of restoring a proper division of attention
between consciousness and behavior. A_ psychologist
may think of himself as chiefly a stream of consciousness.
He may even think of other men as chiefly conscious
selves whose histories they report by word and deed. But
it is only by an extreme bigotry that he can think of a dog
or cat as chiefly a stream or chain or series of consciousness
or consciousnesses. One of the lower animals is so ob-
viously a bundle of original and acquired connections be-
tween situation and response that the student is led to
attend to the whole series, — situation, response and con-
nection or bond, — rather than to just the conscious state
that may or may not be one of the features of the bond.
It is so useful, in understanding the animal, to see what it
does in different circumstances and what helps and what
hinders its learning, that one is led to an intrinsic interest
in varieties of behavior as well as in the kinds of conscious-
ness of which they give evidence.

What each open-minded student of animal psychology
at first hand comes thus to feel vaguely, I propose in this
essay to try to make definite and clear. The studies

=

EL,

The Study of Consciousness and Behavior 5

reprinted in this volume produced in their author an in-
creased respect for psychology as the science of behavior,
a willingness to make psychology continuous with physi-
ology, and a surety that to study consciousness for the sake
of inferring what a man can or will do, is as proper as to
study behavior for the sake of inferring what conscious
states he can or will have. This essay will attempt to
defend these positions and to show further that psychology
may be, at least in part, as independent of introspection
as physics is.

A psychologist who wishes to broaden the content of
the science to include all that biology includes under the
term ‘behavior,’ or all that common sense means by the
words ‘intellect’ and ‘character,’ has to meet certain
objections. The first is the indefiniteness of this content.

The indefiniteness is a fact, but is not in itself objection-
able. It is true that by an animal’s behavior one means
the facts about the animal that are left over after geometry,
physics, chemistry, anatomy and physiology have taken
their toll, and that are not already well looked after by
sociology, economics, history, esthetics and other sciences
dealing with certain complex and specialized facts of be-
havior. It is true that the boundaries of psychology,
from physiology on the one hand, and from sociology,
economics and the like on the other, become dubious and
changeable. But this is in general a sign of a healthy
condition in a science. The pretense that there is an im-
passable cleft between physiology and psychology should
arouse suspicion that one or the other science is studying
words rather than realities.

The same holds against the objection that, if psychology
is the science of behavior, it will be swallowed up by biol-
ogy. When a body of facts treated subjectively, vaguely

6 Animal Intelligence

and without quantitative precision by one science or group
of scientists comes to be treated more objectively, definitely
and exactly by another, it is of course a gain, a symptom of
the general advance of science. That geology may become
a part of physics, or physiology a part of chemistry, is testi-
mony to the advance of geology and physiology. Light
is no less worthy of study by being found to be explainable
by laws discovered in the study of electricity. Meteorology
had to reach a relatively high development to provoke
the wit to say that ‘All the science in meteorology is
physics, the rest is wind.”’

These objections to be significant should frankly assert
that between physical facts and mental facts, between
bodies and minds, between any and all of the animal’s
movements and its states of consciousness, there is an im-
passable gap, a real discontinuity, found nowhere else in
science; and that by making psychology responsible for
territory on both sides of the gap, one makes psychology
include two totally disparate group of facts, things and
thoughts, requiring totally different methods of study.
This is, of course, the traditional view of the scope of
psychology, reiterated in the introductions to the standard
books and often accepted in theory as axiomatic.

It has, however, already been noted that in practice
psychologists do study facts in disregard of this supposed
gap, that the same term refers to facts belonging some on
one side of it and some on the other, and that, in animal
psychology, it seems very unprofitable to try to keep on
one side or the other. Moreover, the practice to which the
study of animal and child psychology leads is, if I under-
stand their writings, justified as a matter of theory by
Dewey and Santayana. If then, as a matter of scientific
fact, human and animal behavior, with or without con-

The Study of Consciousness and Behavior 7

sciousness, seems a suitable subject for a scientific student,
we may study it without a too uneasy sense of philosophic
heresy and guilt.

The writer must confess not only to the absence of any spe-
cial reverence for the supposed axiom, but also to the pres-
ence of a conviction that it is false, the truth being that
whatever feature of any animal, say John Smith, of Homo
sapiens, is studied — its length, its color of hair, its body
temperature, its toothache, its anxiety, or its thinking of
9 x 7— the attitude and methods of the student may prop-
erly be substantially the same.

Of the six facts in the illustration just given, the last
three would by the traditional view be all much alike for
study, and all much unlike any of the first three. The
same kind of science, physical science, would be potent for
the first three and impotent for the last three (save to give
facts about certain physical facts which ‘ paralleled’ them).
Conversely one kind of science, psychology, would by the
traditional view deal with the last three, but have nothing
to say about the first three.

But is there in actual fact any such radical dichotomy
of these six facts as objects of science? Take any task
of science with respect to them, for example, identification.
A score of scientific men, including John Smith himself, are
asked to identify John’s stature at a given moment. Each
observes it carefully, getting, let us say, as measures: 72.10
inches, 72.11, 72.05, 72.08, 72.09, 72.11, etc.

In the case of color of hair each observes as before, the
reports being brown, light brown, brown, light brown,
between light brown and brown, and so forth. }

In the case of body temperature, again, each observes
as before, there being the same variability in the reports;
but John may also observe in a second way, not by observing

8 Animal Intelligence

a thermometer with eyes, but by observing the temperature
of his body through other sense-organs so situated that
they lead to knowledge of only his own body’s tempera-
ture. It is important to note that for efficient knowledge
of his own body-temperature, John does not use the sense
approach peculiar to him, but that available for all ob-
servers. He identifies and measures his ‘feverishness’ by
studying himself as he would study any other animal, by
thermometer and eye.

In the case of the toothache the students proceed as
before, except that they use John’s gestures, facial ex-
pression, cries and verbal reports, as well as his mere
bodily structure and condition. They not only observe the
cavities in his teeth, the signs of ulcer and the like, but they
also ask him, tapping a tooth, “Does it hurt?” “How
long has it hurt?” “Does it hurt very much?” and the
like. John, if their equal in knowledge of dentistry, would
use the same methods, testing himself, asking himself
questions and using the replies made by himself to himself
in inner speech. But, as with temperature, he would get
data, for his identification of the toothache, from a source
unavailable for the others, the sense-organs in his teeth.

It is worth while to consider how they and he would pro-
ceed to an exact identification or measure of the intensity
of his toothache such as was made of his stature or body-
temperature. First, they would need a scale of toothaches
of varying intensities. Next, they would need means of
comparing the intensity of his toothache with those of
this scale to see which it was most like. Given this scale
and means of comparison, they would turn John’s attention
from the original toothache to one of given intensity, and
compare the two, both by his facial expression, gestures and
the like, and by the verbal reports made. John would

The Study of Consciousness and Behavior 9

do likewise, reporting to himself instead of to them. The
similarity of the procedure to that in studying a so-called
physical fact is still clearer if we suppose a primitive con-
dition of the scales of length and temperature. Suppose
for example that for the length of aman we had only
‘short’ or ‘tall as a deer,’ ‘medium’ or ‘tall as a moose,’
and ‘tall’ or ‘tall as a horse’; and for the intensity of the
toothache of a man ‘little’ or ‘intense as a _pin-prick,’
‘medium’ or ‘intense as a knife-cut,’ and ‘great’ or ‘in-
tense as a spear-thrust.’ Then obviously the only difference
between the identification of the length of a man’s body and
the identification of the intensity of his toothache would
be that the latter was made by all on the basis of behavior
as well as anatomy, and made by the individual having
it on the basis of data from an additional sense-organ.

In actual present practice, if observers were asked to
identify the intensity of John’s toothache on a scale run-
ning from zero intensity up, the variability of the reports
would be very great in comparison with those of stature
or body-temperature. Supposing the most intense tooth-
ache to be called K, we might well have reports of from
say .300 K to .450 K, some observers identifying the fact
with a condition one and a half times as intense as that
chosen by others. But such a variability might also occur
in primitive men’s judgments of length or temperature.

It is important to note that the accuracy of John’s own
identification of it depends in any case on his knowledge
of the scale and his power of comparing his toothache there-
with. Well-trained outside observers might identify the
intensity of John’s toothache more accurately than he
could.

In the case of John’s anxiety, the most striking fact is
the low degree of accuracy in identification. The quality of

Ke) Animal Intelligence

the anxiety and its intensity would both be so crudely
measured by present means that even if the observers
were from the score of most competent psychologists, their
reports would probably be not much better than, say, the
descriptions now found in masterpieces of fiction and drama.
Science could not tell at all closely how much John’s anxiety
at this particular time resembled either his anxiety on
some other occasion or anything else. This inferiority
is due in part to the fact that the manifestations of anxiety
in behavior, including verbal reports, are so complicated
by facts other than the anxiety itself, by, for example,
the animal’s health, temperament, concomitant ideas
and emotions, knowledge of language, clearness in expres-
sion and the like. It is due in part to the very low status
of our classification of kinds of anxieties and of our units
and scales for measuring the amount of each kind. Hence
the variation amongst observers would be even greater
than in the case of the toothache, and the confidence of
all in their judgments would be less, and far, far less than
their confidence in their judgment of John’s stature. The
best possible present knowledge of John’s anxiety, though
scientific in comparison with ordinary opinion about it,
would seem grossly unscientific in comparison with knowl-
edge of his stature or weight. Knowledge of the anxiety
would improve with better knowledge of its manifestations,
including verbal reports by John, and with better means of
classification and measurement.

John’s knowledge of his own anxiety would be in part the
same as that of the other observers. He too would judge
his condition by its external manifestations, would name
its sort and rate its amount on the basis of his own behavior,
as he saw his own face, heard his own groans, and read the
notes he wrote describing his condition. But he would

The Study of Consciousness and Behavior 11

also, as with the toothache, have data from internal sense-
organs and perhaps from centrally initiated neural actions.
In so far as he could report these data to himself for use
in scientific thought more efficiently than he could report
them to the other observers, he would have, as with the
toothache, an advantage comparable to the advantage
of a criminologist who happened also to be or to have been
a thief, or of a literary critic who happened to have written
what he judged. It is important to note that only in so
far as he who has ‘immediate experience’ of or participates
in or is ‘directly conscious’ of the anxiety, reports it to
himself as thinker or scientific student, in common with
the other nineteen, that this advantage accrues. To
really be or have the anxiety is not to correctly know it.
An insane man must become sane in order to know his
insane condition. Bigotry, stupidity and false reasoning
can be understood only by one who never was them or has
ceased to be them.

In our last illustration, John’s thinking of ‘9 X 7 equals
63,’ the effect on John’s behavior may be so complicated
by other conditions in John, and is so subject to the par-
ticular conditions which we name John’s ‘will,’ that the
observers would often be at loss except for John’s verbal
report. Not that the observer is restricted to that. If

21
John does the example x fe in the usual way, it is a very
safe inference that he thought 9 x 7 equals 63, regardless
of the absence of a verbal report from him. But often there
is little else to go by. To John himself, on the contrary,
it is easier to be sure that he is thinking of 9 X 7 equals
63, than that he has a particular sort and strength of tooth-
ache. Consequently if we suppose John to be thinking
of that fact while under observation, and the twenty ob-

ree Animal Intelligence

servers to be required to identify the fact he is thinking
of, it is sure that there might be an enormous variability in
their guesses as to what the fact was and that his testimony
might be worth far more than that of all the other nineteen
without his testimony. His observation is influenced by
the action of the neurones in his central nervous system as
theirs is not, and, in the case of the thought ‘9g X 7 equals
63,’ the action of these neurones is of special importance.

Our examination of the way science treats these six facts
shows no impassable cleft between knowledge of a man’s
body and knowledge of his mind. Scientific statements
about the toothache, anxiety and numerical judgment are
in general more variable than statements about length,
hair-color and body-temperature, but there is here no
difference save of degree. Some physical facts, such as
hair-color, eye-color or health, are, in fact, judged more
variably than some mental facts, such as rate of adding,
accuracy of perception of a certain sort and the like. So
far as the lack of agreement amongst impartial observers
goes, there is continuity from the identification of a length
to that of an ideal.

Scientific judgments about the facts of John’s mind
also depend, in general, more upon his verbal reports than
do judgments about his body. But here also the difference
is only of degree. The physician studying wounds, ulcers,
tumors, infections and other facts of a man’s body may
depend more upon his verbal reports than does the moral-
ist who is studying the man’s character. Verbal reports
too are themselves a gradual and continuous extension of
coarser forms of behavior. They signify consciousness
no more truly than do signs, gestures, facial expression
and the general bodily motions of pursuit, retreat, avoid-
ance or seizure.

The Study of Consciousness and Behavior 13

Nor is it true that physical facts are known to many
observers and mental facts to but one, who 7s or has or
directly experiences them. If it were true, sociology,
- economics, history, anthropology and the like would
either be physical sciences or represent no knowledge at
all. The kind of knowledge of which these sciences and
the common judgments of our fellow men are made up is
knowledge possessed by many observers in common, the
individual of whom the facts is known, knowing the fact
in part in just the same way that the others know it.

The real difference between a man’s scientific judgments
about himself and the judgment of others about him is
that he has added sources of knowledge. Much of what
goes on in him influences him in ways other than those
in which it influences other men. But this difference is
not coterminous with that between judgments about his
‘mind’ and about his ‘body.’ As was pointed out in the
case of body-temperature, a man knows certain facts about
his own body in such additional ways.

Furthermore, there is no more truth in the statement
that a man’s pain or anxiety or opinions are matters of
direct consciousness, pure experience, than in the statement
that his length, weight and temperature are, or that the sun,
moon and stars are. If by the pain we must mean the pain
as felt by some one, then by the sun we can mean only the
sun as seen by some one. Pain and sun are equally subjects
for a science of ‘consciousness as such.’ But if by the
sun is meant the sun of common sense, physics and astron-
omy, the sun as known by any one, then by the pain we
can mean the pain of medicine, economics and sociology, the
pain as known by any one, and by the sufferer long after
he was or had it.

All facts emerge from the matrix of pure experience;

14 Animal Intelligence

but they become facts for science only after they have
emerged therefrom. A man’s anxiety may be the anxiety
as directly felt by the man, or as thought of by him, or as
thought of by the general consensus of scientific observers.
But so also may be his body-temperature or weight or the
composition of the blood in his veins. There can be no
valid reason other than a pragmatic one for studying a
man’s anxiety solely as felt by him while studying his body-
temperature as thought of by him and others. And the
practical reasons are all in favor of studying all facts as they
exist for any impartial observer. A man’s mind as it is to
thinking men is all that thinking men can deal with and
all that they have any interest in dealing with.

Finally, the subject-matter of psychology is not sharply
marked off from the subject-matter of physiology by being
absolutely non-spatial. On the contrary, the toothache,
anxiety and judgment are referred unequivocally, by every
sane man who thinks of them, to the space occupied by
the body of the individual in question. That is the surest
fact about them. It is true that we do not measure the
length, height, thickness and weight of an animal’s pain
or anxiety, but neither do we those of his pulse, temper-
ature, health, digestion, metabolism, patellar reflex or
heliotropism.

Two noteworthy advantages are secured by the study
of behavior. First, the evidence about intellect and
character offered by action and the influence of intellect
and character upon action are given due attention. Second,
the connections of conscious states are studied as well as
their composition.

The mind or soul of the older psychology was the cause
not only of consciousness, but also of modifiability in
thought and action. It was the substance or force in man

The Study of Consciousness and Behavior 15

whereby he was sensitive to certain events, was able to
make certain movements, and not only had ideas but con-
nected them one with another and with various impressions
and acts. It was supposed to account for actual bodily
action as well as for the action-consciousness. It explained
the connections between ideas as well as their internal
composition. If a modern psychologist defines mind as the
sum total of consciousness, and lives up to that definition,
he omits the larger portion of the task of his predecessors.
To define our subject-matter as the nature and behavior
of men, beginning where anatomy and physiology leave
off, is, on the contrary, to deliberately assume responsibility
for the entire heritage. Behavior includes consciousness
and action, states of mind and their connections.

Even students devoted to ‘consciousness as such’ must
admit that the movements of an animal and their connec-
tions with other features of his life deserve study, by even
their kind of psychologist. For the fundamental means
of knowing that an animal has a certain conscious state
are knowledge that it makes certain movements and knowl-
edge of what conscious states are connected with those
movements. Knowledge of the action-system of an animal
and its connections is a prerequisite to knowledge of its
stream of consciousness.

There are better reasons for including the action-system
of an animal in the psychologist’s subject-matter. An
animal’s conscious stream is of no account to the rest of
the world except in so far as it prophesies or modifies his
action. There can be no moral warrant for studying
man’s nature unless the study will enable us to control
his acts. If a psychologist is to study man’s consciousness
without relation to movement, he might as well fabricate

1 Unless one assumes telepathic influences.

16 Animal Intelligence

imaginary consciousnesses to describe and analyze. The
lovers of consciousness for its own sake often do this un-
wittingly, but would scarcely take pride therein!

The truth of the matter is, of course, that an animal’s
mind is, by any definition, something intimately associated
with his connection-system or means of binding various
physical activities to various physical impressions. The
whole series — external situations and motor responses as
well as their bonds — must be studied to some extent in
order to understand whatever we define as mind. The
student of behavior, by frankly accepting the task of supply-
ing any needed information not furnished by physiology,
and of studying the animal in action as well as in thought,
is surer of getting an adequate knowledge of whatever
features of an animal’s life may be finally awarded the title
of mind.

The second advantage in studying total behavior rather
than consciousness as such is that thereby the connections
of mental facts one with another and with non-mental facts
receive due attention.

The original tendencies to connect certain thoughts,
feelings and acts with certain situations — tendencies
which we call reflexes, instincts and capacities — are not
themselves states of consciousness; nor are the acquired
connections which we call habits, associations of ideas,
tendencies to attend, select and the like. No state of
consciousness bears within itself an account of when and
how it will appear, or of what bodily act will be its sequel.
What any given person will think in any given situation is
unpredictable by mere descriptions and analyses of his
previous thoughts each by itself. To understand the when,
how and why of states of consciousness one must study
other facts than states of consciousness. These non-

The Study of Consciousness and Behavior 17

conscious relations or connections, knowledge of which
informs us of the result to come from the action of a given
situation on a given animal, may be expected to be fully
half of the subject-matter of mental science.

As was noted in the early pages of this chapter, the psy-
chologist commonly does adopt the attitude of treating mind
as a system of connections long enough to give some account
of the facts of instinct, habit, memory, and the like. But
the dogma that psychology deals exclusively with the inner
stream of mind-stuff has made these accounts needlessly
scanty and vague.

One may appreciate fully the importance of finding out
whether the attention-consciousness is clearness or is some-
thing else, and whether it exists in two or three discrete
degrees or in a continuous series of gradations, and still
insist upon the equal importance of finding out to what
facts and for what reasons human beings do attend. There
would appear, for example, to be an unfortunate limitation
to the study of human nature by the examination of its
consciousnesses, when two eminent psychologists, writing
elaborate accounts of attention from that point of view,
tell us almost nothing whereby we can predict what any
given animal will attend to in any given situation, or can
cause in any given animal a state of attention to any given
fact.

One may enjoy the effort to define the kind of mind-stuff
in which one thinks of classes of facts, relations between
facts and judgments about facts, and still protest that a
proper balance in the study of intellect demands equal or
greater attention to the problems of why any given animal
thinks of any given fact, class or relation in any given
situation and why he makes this or that judgment about it.

In the case of the so-called action-consciousness the

Cc

18 Animal Intelligence

neglect of the connections becomes preposterous. The
adventitious scraps of consciousness called ‘willing’ which
may intervene between a situation productive of a given
act and the act itself are hopelessly uninstructive in com-
parison with the bonds of instinct and habit which cause the
situation to produce the act. In conduct, at least, that
kind of psychology which Santayana calls ‘the perception
of character’ seems an inevitable part of a well-balanced
science of human nature. I quote from his fine descrip-
tion of the contrast between the external observation of a
mind’s connections and the introspective recapitulation of
its conscious content, though it is perhaps too pronounced
and too severe.

“Perception of Character. —'There is, however, a wholly
different and far more positive method of reading the mind,
or what in a metaphorical sense is called by that name.
This method is to read character. Any object with which
we are familiar teaches us to divine its habits; slight
indications, which we should be at a loss to enumerate
separately, betray what changes are going on and what
promptings are simmering in the organism. . . . The gift
of reading character . . . is directed not upon consciousness
but upon past or eventual action. Habits and passions,
however, have metaphorical psychic names, names indicat-
ing dispositions rather than particular acts (a disposition
being mythically represented as a sort of wakeful and haunt-
ing genius waiting to whisper suggestions in a man’s ear).
We may accordingly delude ourselves into imagining that
a pose or a manner which really indicates habit indicates
feeling instead.

‘Conduct Divined, Consciousness Ignored... . As the
weather prophet reads the heavens, so the man of expe-
rience reads other men. Nothing concerns him less than

The Study of Consciousness and Behavior 19

their consciousness; he can allow that to run itself off
when he is sure of their temper and habits. A great
master of affairs is usually unsympathetic. His obser-
vation is not in the least dramatic or dreamful, he does
not yield himself to animal contagion or reénact other
people’s inward experience. He is too busy for that,
and too intent on his own purposes. His observation,
on the contrary, is straight calculation and inference,
and it sometimes reaches truths about people’s character
and destiny which they themselves are very far from
divining. Such apprehension is masterful and odious to
weaklings, who think they know themselves because they
indulge in copious soliloquy (which is the discourse of
brutes and madmen), but who really know nothing of
their own capacity, situation, or fate.” !

Mr. Santayana elsewhere hints that both psychology and
history will become studies of human behavior considered
from without, — a part, that is, of what he calls physics, —
if they are to amount to much.

Such a prediction may come true. But for the present
there is no need to decide which is better — to study an
animal’s self as conscious, its stream of direct experience,
or to study the intellectual and moral nature that causes its
behavior in thought and action and is known to many
observers. Since worthy men have studied both, both are
probably worthy of study. All that I wish to claim is the
right of a man of science to study an animal’s intellectual
and moral behavior, following wherever the facts lead — to
“the sum total of human experience considered as dependent
upon the experiencing person,” to the self as conscious, or to
a connection-system known to many observers and born
and bred in the animal’s body.

1 Reason in Common Sense, p. 154 fi.

CHAPTER II

ANIMAL INTELLIGENCE; AN EXPERIMENTAL STUDY OF THE
ASSOCIATIVE PROCESSES IN ANIMALS!

THIS monograph is an attempt at an explanation of the
nature of the process of association in the animal mind. In-
asmuch as there have been no extended researches of a char-
acter similar to the present one either in subject-matter or
experimental method, it is necessary to explain briefly its
standpoint.

Our knowledge of the mental life of animals equals in
the main our knowledge of their sense-powers, of their
instincts or reactions performed without experience, and
of their reactions which are built up by experience. Con-
fining our attention to the latter, we find it the opinion of
the better observers and analysts that these reactions can
all be explained by the ordinary associative processes with-
out aid from abstract, conceptual, inferential thinking.
These associative processes then, as present in animals’
minds and as displayed in their acts, are my subject-matter.
Any one familiar in even a general way with the literature
of comparative psychology will recall that this part of the
field has received faulty and unsuccessful treatment. The
careful, minute and solid knowledge of the sense-organs of
animals finds no counterpart in the realm of associations and
habits. We do not know how delicate or how complex or
how permanent are the possible associations of any given
group of animals. And although one would be rash who
said that our present equipment of facts about instincts

1This chapter originally appeared as Monograph Supplement No. 8 of

the Psychological Review.
20

Experimental Study of Associative Processes 21

was sufficient or that our theories about it were surely sound,
yet our notion of what occurs when a chick grabs a worm
are luminous and infallible compared to our notion of what
happens when a kitten runs into the house at the familiar
call. The reason that they have satisfied us as well as they
have is just that they are so vague. We say that the kitten
associates the sound ‘kitty kitty’ with the experience of
nice milk to drink, which does very well for a common-sense
answer. It also suffices as a rebuke to those who would
have the kitten ratiocinate about the matter, but it fails
to tell what real mental content is present. Does the kitten
feel “sound of call, memory-image of milk in a saucer in the
kitchen, thought of running into the house, a feeling, finally,
of ‘I will run in’”’? Does he perhaps feel only the sound
of the bell and an impulse to run in, similar in quality to
the impulses which make a tennis player run to and fro
when playing? The word ‘association’ may cover a multi-
tude of essentially different processes, and when a writer
attributes anything that an animal may do to association,
his statement has only the negative value of eliminating
reasoning on the one hand and instinct on the other.
His position is like that of a zodlogist who should to-day
class an animal among the ‘worms.’ To give to the word a
positive value and several definite possibilities of meaning
is one aim of this investigation.

The importance to comparative psychology in general of
a more scientific account of the association-process in ani-
mals is evident. Apart from the desirability of knowing
all the facts we can, of whatever sort, there is the especial
consideration that these associations and consequent habits
have an immediate import for biological science. In the
higher animals the bodily life and preservative acts are
largely directed by these associations. They, and not

22 Animal Intelligence

instinct, make the animal use the best feeding grounds,
sleep in the same lair, avoid new dangers and profit by new
changes in nature. Their higher development in mammals
is a chief factor in the supremacy of that group. This,
however, is a minor consideration. The main purpose of
the study of the animal mind is to learn the development of
mental life down through the phylum, to trace in particular
the origin of human faculty. In relation to this chief pur-
pose of comparative psychology the associative processes
assume a role predominant over that of sense-powers or
instinct, for in a study of the associative processes lies the
solution of the problem. Sense-powers and instincts have
changed by addition and supersedence, but the cognitive
side of consciousness has changed not only in quantity but
also in quality. Somehow out of these associative processes
have arisen human consciousnesses with their sciences and
arts and religions. The association of ideas proper, imagi-
nation, memory, abstraction, generalization, judgment, in-
ference, have here their source. And in the metamorphosis
the instincts, impulses, emotions and sense-impressions
have been transformed out of their old natures. For the
origin and development of human faculty we must look
to these processes of association in lower animals. Not
only then does this department need treatment more, but
promises to repay the worker better.

Although no work done in this field is enough like the
present investigation to require an account of its results,
the method hitherto in use invites comparison by its contrast
and, as I believe, by its faults. In the first place, most of
the books do not give us a psychology, but rather a eulogy,
of animals. They have all been about animal zntelligence,
never about animal stupidity. Though a writer derides
the notion that animals have reason, he hastens to add that

Experimental Study of Associative Processes 23

they have marvelous capacity of forming associations, and
is likely to refer to the fact that human beings only rarely
reason anything out, that their trains of ideas are ruled
mostly by association, as if, in this latter, animals were on a
par with them. The history of books on animals’ minds
thus furnishes an illustration of the well-nigh universal tend-
ency in human nature to find the marvelous wherever it
can. We wonder that the stars are so big and so far apart,
that the microbes are so small and so thick together, and
for much the same reason wonder at the things animals
do. ‘They used to be wonderful because of the mysterious,
God-given faculty of instinct, which could almost remove
mountains. More lately they have been wondered at be-
cause of their marvelous mental powers in profiting by
experience. Now imagine an astronomer tremendously
eager to prove the stars as big as possible, or a bacteriologist
whose great scientific desire is to demonstrate the microbes
to be very, very little! Yet there has been a similar eager-
ness on the part of many recent writers on animal psychology
to praise the abilities of animals. It cannot help leading to
partiality in deductions from facts and more especially in
the choice of facts for investigation. How can scientists
who write like lawyers, defending animals against the charge
of having no power of rationality, be at the same time
impartial judges on the bench? Unfortunately the real
work in this field has been done in this spirit. The level-
headed thinkers who might have won valuable results
have contented themselves with arguing against the theories
of the eulogists. They have not made investigations of
their own.

In the second place, the facts have generally been derived
from anecdotes. Now quite apart from such pedantry as
insists that a man’s word about a scientific fact is worthless

24 Animal Intelligence

unless he is a trained scientist, there are really in this field
special objections to the acceptance of the testimony about
animals’ intelligent acts which one gets from anecdotes.
Such testimony is by no means on a par with testimony
about the size of a fish or the migration of birds, etc. For
here one has to deal not merely with ignorant or inaccurate
testimony, but also with prejudiced testimony. Human
folk are as a matter of fact eager to find intelligence in
animals. They like to. And when the animal observed is
a pet belonging to them or their friends, or when the story
is one that has been told as a story to entertain, further
complications are introduced. Nor is this all. Besides
commonly misstating what facts they report, they report
only such facts as show the animal at his best. Dogs get
lost hundreds of times and no one ever notices it or sends an
account of it to a scientific magazine. But let one find his
way from Brooklyn to Yonkers and the fact immediately
becomes a circulating anecdote. Thousands of cats on
thousands of occasions sit helplessly yowling, and no one
takes thought of it or writes to his friend, the professor ;
but let one cat claw at the knob of a door supposedly as a
signal to be let out, and straightway this cat becomes the
representative of the cat-mind in all the books. The un-
conscious distortion of the facts is almost harmless com-
pared to the unconscious neglect of an animal’s mental life
until it verges on the unusual and marvelous. It is as if
some denizen of a planet where communication was by
thought-transference, who was surveying humankind and
reporting their psychology, should be oblivious to all our
intercommunication save such as the psychical-research
society has noted. If he should further misinterpret the
cases of mere coincidence of thoughts as facts comparable
to telepathic communication, he would not be more wrong

Experimental Study of Associative Processes 25

than some of the animal psychologists. In short, the
anecdotes give really the abnormal or supernormal psy-
chology of animals.

Further, it must be confessed that these vices have been
only ameliorated, not obliterated, when the observation is
first-hand, is made by the psychologist himself. For as men
of the utmost scientific skill have failed to prove good
observers in the field of spiritualistic phenomena,! so biolo-
gists and psychologists before the pet terrier or hunted
fox often become like Samson shorn. They, too, have
looked for the intelligent and unusual and neglected the
stupid and normal.

Finally, in all cases, whether of direct observation or
report by good observers or bad, there have been three other
defects. Only a single case is studied, and so the results
are not necessarily true of the type; the observation is not
repeated, nor are the conditions perfectly regulated; the
previous history of the animal in question is not known.
Such observations may tell us, if the observer is perfectly
reliable, that a certain thing takes place; but they cannot
assure us that it will take place universally among the ani-
mals of that species, or universally with the same animal.
Nor can the influence of previous experience be estimated.
All this refers to means of getting knowledge about what
animals do. The next question is, “‘What do they feel?”
Previous work has not furnished an answer or the material
for an answer to this more important question. Nothing
but carefully designed, crucial experiments can. In aban-

1T do not mean that scientists have been too credulous with regard to
spiritualism, but am referring to the cases where ten or twenty scientists
have been sent to observe some trick-performance by a spiritualistic ‘mee
dium,’ and have all been absolutely confident that they understood the secret
of its performance, each of them giving a totally different explanation.

26 Animal Intelligence

doning the old method one ought to seek above all to
replace it by one which will not only tell more accurately
what they do, and give the much-needed information how
they do it, but also inform us what they feel while they act.
To remedy these defects, experiment must be substituted
for observation and the collection of anecdotes. Thus you
immediately get rid of several of them. You can repeat the
conditions at will, so as to see whether or not the animal’s
behavior is due to mere coincidence. A number of animals
can be subjected to the same test, so as to attain typical
results. The animal may be put in situations where its
conduct is especially instructive. After considerable pre-
liminary observation of animals’ behavior under various
conditions, I chose for my general method one which, simple
as it is, possesses several other marked advantages besides
those which accompany experiment of any sort. It was
merely to put animals when hungry in inclosures from which
they could escape by some simple act, such as pulling at a
loop of cord, pressing a lever, or stepping ona platform. (A
detailed description of these boxes and pens will be given
later.) The animal was put in the inclosure, food was left
outside in sight, and his actions observed. Besides record-
ing his general behavior, special notice was taken of how he
succeeded in doing the necessary act (in case he did succeed),
and a record was kept of the time that he was in the box
before performing the successful pull, or clawing, or bite.
This was repeated until the animal had formed a perfect
association between the sense-impression of the interior of
that box and the impulse leading tothe successful movement.
When the association was thus perfect, the time taken to
escape was, of course, practically constant and very short.
If, on the other hand, after a certain time the animal did
not succeed, he was taken out, but not fed. If, after a suffi-

Experimental Study of Associative Processes 27

cient number of trials, he failed to get out, the case was re-
corded as one of complete failure. Enough different sorts
of methods of escape were tried to make it fairly sure that
association in general, not association of a particular sort of
impulse, was being studied. Enough animals were taken
with each box or pen to make it sure that the results were
not due to individual peculiarities. None of the animals
used had any previous acquaintance with any of the
mechanical contrivances by which the doors were opened.
So far as possible the animals were kept in a uniform state
of hunger, which was practically utter hunger.t That is,
no cat or dog was experimented on, when the experi-
ment involved any important question of fact or theory,

1 The phrase ‘practically utter hunger’ has given rise to misunderstand-
ings. I have been accused of experimenting with starving or half-starved
animals, with animals brought to a state of fear and panic by hunger, and
the like!

The desideratum is, of course, to have the motive as nearly as possible of
equal strength in each experiment with any one animal with any one act.
That is, the animal should be as hungry at the tenth or twentieth trial as at
the first. To attain this, the animal was given after each ‘success’ only
a very small bit of food as a reward (say, for a young cat, one quarter of a
cubic centimeter of fish or meat) and tested not too many times on any one
day. ‘Utter hunger’ means that no diminution in his appetite was noted
and that at the close of the experiment for the day he would still eat a hearty
meal. After the experiments for the day were done, the cats received
abundant food to maintain health, growth and spirits, but commonly some-
what less than they would of their own accord have taken. No one of the
many visitors to the room mentioned anything extraordinary or distressful
in the animals’ condition. There were no signs of fear or panic.

Possibly I was wrong in choosing the term ‘utter hunger’ to denote the
hunger of an animal in good, but not pampered, condition and without food
for fourteen hours. It is not sure, however, that the term ‘utter hunger’
is inappropriate. The few reports made of experiments in going without
food seem to show that, in health, the feeling of hunger reaches its maximum
intensity very early. It is of course not at all the same thing as the complex
of discomforts produced by long-continued insufficiency of food. Hunger
is not at all a synonym for starvation.

28 Animal Intelligence

unless I was sure that his motive was of the standard
strength. With chicks this is not practicable, on account of
their delicacy. But with them dislike of loneliness acts as
a uniform motive to get back to the other chicks. Cats (or
rather kittens), dogs and chicks were the subjects of the
experiments. All were apparently in excellent health, save
an occasional chick.

By this method of experimentation the animals are put
in situations which call into activity their mental functions
and permit them to be carefully observed. One may, by
following it, observe personally more intelligent acts than
are included in any anecdotal collection. And this actual
vision of animals in the act of using their minds is far more
fruitful than any amount of history of what animals have
done without the history of how they did it. But besides
affording this opportunity for ‘purposeful and systematic
observation, our method is valuable because it frees the
animal from any influence of the observer. The animal’s
behavior is quite independent of any factors save its own
hunger, the mechanism of the box it is in, the food outside,
and such general matters as fatigue, indisposition, etc.
Therefore the work done by one investigator may be re-
peated and verified or modified by another. No personal
factor is present save in the observation and interpretation.
Again, our method gives some very important results
which are quite uninfluenced by any personal factor in any
way. ‘The curves showing the progress of the formation of
associations, which are obtained from the records of the
times taken by the animal in successive trials, are facts which
may be obtained by any observer who can tell time. They
are absolute, and whatever can be deduced from them is
sure. So also the question of whether an animal does or
does not form a certain association requires for an answer

Experimental Study of Associative Processes 29

no higher qualification in the observer than a pair of eyes.
The literature of animal psychology shows so uniformly and
often so sadly the influence of the personal equation that
any method which can partially eliminate it deserves a trial.

Furthermore, although the associations formed are such
as could not have been previously experienced or provided
for by heredity, they are still not too remote from the ani-
mal’s ordinary course of life. They mean simply the con-
nection of a certain act with a certain situation and resultant
pleasure, and this general type of association is found
throughout the animal’s life normally. The muscular
movements required are all such as might often be required
of the animal. And yet it will be noted that the acts re-
quired are nearly enough like the acts of the anecdotes to
enable one to compare the results of experiment by this
method with the work of the anecdote school. Finally, it
may be noticed that the method lends itself readily to ex-
periments on imitation.

We may now start in with the description of the apparatus
and of the behavior of the animals.’

DESCRIPTION OF APPARATUS

The shape and general apparatus of the boxes which were
used for the cats is shown by the accompanying drawing of
box K. Unless special figures are given, it should be under-
stood that each box is approximately 20 inches long, by 15
broad, by 12 high. Except where mention is made to the
contrary, the door was pulled open by a weight attached toa

1 The experiments now to be described were for the most part made in the
Psychological Laboratory of Columbia University during the year ’97-’98,
but a few of them were made in connection with a general preliminary

investigation of animal psychology undertaken at Harvard University in
the previous year.

30 Animal Intelligence

string which ran over a pulley and was fastened to the door,
just as soon as the animal loosened the bolt or bar which
held it. Especial care was taken not to have the widest
openings between the bars at all near the lever, or wire
loop, or what not, which governed the bolt on the door.

ExrGs r

For the animal instinctively attacks the large openings first,
and if the mechanism which governs the opening of the door
is situated near one of them, the animal’s task is rendered
easier. You do not then get the association-process so free
from the helping hand of instinct as you do if you make the
box without reference to the position of the mechanism to
be set up within it. These various mechanisms are so
simple that a verbal description will suffice in most cases.
The facts which the reader should note are the nature of the
movement which the cat had to make, the nature of the
object at which the movement was directed, and the posi-
tion of the object in the box. In some special cases atten-

Experimental Study of Assocratwe Processes 31

tion will also be called to the force required. In general,
however, that was very slight (20 to 100 grams if applied
directly). The various boxes will be designated by capital
letters.

A. A string attached to the bolt which held the door ran
up over a pulley on the front edge of the box, and was tied
to a wire loop (24 inches in diameter) hanging 6 inches
above the floor in front center of box. Clawing or biting it,
or rubbing against it even, if in a certain way, opened the
door. We may call this box A ‘O at front.’

B. A string attached to the bolt ran up over a pulley on
the front edge of the door, then across the box to another
pulley screwed into the inside of the back of the box 14
inches below the top, and passing over it ended in a wire loop
(3 inches in diameter) 6 inches above the floor in back center
of box. Force applied to the loop or fo the string as it ran
across the top of the box between two bars would open the
door. We may call B ‘O at back.’

Br. In Br the string ran outside the box, coming down
through a hole at the back, and was therefore inaccessible
and invisible from within. Only by pulling the loop could
the door be opened. Br may be called ‘O at back 2d.’

C. A door of the usual position and size (as in Fig. 1) was
kept closed by a wooden button 3% inches long, § inch
wide, $ inch thick. This turned on a nail driven into the
box 3 inch above the middle of the top edge of the door.
The door would fall inward as soon as the button was turned
from its vertical to a horizontal position. A pull of 125
grams would do this if applied sideways at the lowest point
of the button 2 inches below its pivot. The cats usually
clawed the button round by downward pressure on its top
edge, which was 14 inches above the nail. Then, of course,
more force was necessary. C may be called ‘ Button.’

32 Animal Intelligence

D. The door was in the extreme right of the front.
A string fastened to the bolt which held it ran up
over a pulley on the top edge and back to the top edge
of the back side of the box (3 inches in from the right
side) and was there firmly fastened. The top of the box
was of wire screening and arched over the string ? inch
above it along its entire length. A slight pull on the
string anywhere opened the door. This box was 20 x 16,
but a space 7 X 16 was partitioned off at the left by a wire
screen. D may be called ‘String.’

Di was the same box as B, but had the string fastened
firmly at the back instead of running over a pulley and
ending in a wire loop. We may call it ‘String 2d.’

E. A string ran from the bolt holding the door up over a
pulley and down to the floor outside the box, where it was
fastened 2 inches in front of the box and 1% inches to the
left of the door (looking from the inside). By poking a paw
out between the bars and pulling this string inward the door
would be opened. We may call E ‘String outside.’

In F the string was not fastened to the floor but ended ina
loop 2% inches in diameter which could be clawed down so as
to open the door. Unless the pull was in just the right direc-
tion, the string was likely to catch on the pulley. This loop
hung 3 inches above the floor, and 1? inches in front of the
box. We may call F ‘String outside unfastened.’

G was a box 29 X 20% X 22%, with a door 29 X 12 hinged
on the left side of the box (looking from within), and kept
closed by an ordinary thumb latch placed 15 inches from
the floor. The remainder of the front of the box was closed
in by wooden bars. The door was a wooden frame covered
with screening. It was not arranged so as to open as soon as
the latch was lifted, but required a force of 400 grams, even
when applied to the best advantage. The bar of the thumb

Experimental Study of Associative Processes 33

latch, moreover, would fall back into place again unless the
door were pushed out at least a little. The top of this box
was not of bars or screening, but solid. We may call G
‘Thumb laich.’

H was, except for the opening where the door was situated,
a perfectly solid and dark box. In the front was cut an
opening about 9 X 7 inches. A wooden frame covered with
wire netting hung in front of this. It was fastened to the
box only by a screw through the middle of the frame’s top
piece, and could therefore be pushed to either side so as to
permit escape from the box if it were prevented from swing-
ing back into place.

I was a box 12 X 14 X 23. The door was 8 inches wide, 4
high, and hinged at the left side. It was held closed by a
wooden bar which moved easily on a pivot and which could
be pushed up by another bar which projected 5 inches into
the box. This second bar was pivoted so that downward
pressure on it pushed the first bar up and let the door swing
open. The second bar entered the box at a point 4 inches
above the floor and 24 inches in from the right side of the
box. In its normal position its inner end was 5% inches
above the floor. A depression of 2 inches at that end was
necessary to open the door. Of course, nearer the pivot a
shorter depression would do. The front of the box was
closed by bars, but the rest by solid boards. We may call I
‘ Lever.’

J was the same as B except that the door was not opened
by a weight as soon as the bolt was pulled up. On the con-
trary, the door was held closed by a small piece of board
(4 xX 3144 x 34 thick) placed against it outside. After
pulling the loop at the back the cat had to knock down
this support and push the door open. We may call J
‘Double.’

D

34 Animal Intelligence

K was a box arranged so that three separate acts were re-
quired to open the door, which was held by two bolts at the
top and two bars outside. One of the bolts was connected
with a platform in the back center of the box so that depress-
ing the platform raised the bolt. The other was raised by a
string which ran up over a pulley in the front, across the
box 1 inch above the bars, over a pulley near the corner of
the box, and down to the floor, where it was fastened. Pull-
ing on this string, either by clawing at it where it was run-
ning vertically from the last pulley to the floor, or by putting
the paw out between the bars which covered the top of the
box, and clawing the string downward, would raise the bolt.
If both bolts were raised and ezther bar was pushed up or
down far enough to be out of the way, the cat could escape.
K, or ‘Trifle,’ as it may be called, is the box reproduced in
Figure 1.

L was a box that also required three acts to open the door.
It was a combination of A (O at front), D (string), I (lever).
The lever or bar to be depressed was 2 inches to the right of
the door, which was in the front center. The string tobe
clawed or bitten ran from front center to back center 1 inch
below the top of the box.

Z was a box with back and sides entirely closed, with
front and top closed by bars and screening, with a small
opening in the left-hand corner. A box was held in front
of this and drawn away when the cats happened to lick
themselves. Thus escape and food followed always upon
the impulse to lick themselves, and they soon would im-
mediately start doing so as soon as pushed into the box.
The same box was used with the impulse changed to that
for scratching themselves. The size of this box was
I5 X 10 X 16.

Experimental Study of Associative Processes 35

EXPERIMENTS WITH CATS

In these various boxes were put cats from among the
following. I give approximately their ages while under
experiment.

No. 1. 8-10 months. No. 7. 3-5 months.
No. 2. 5-7 months. No. 8. 6-614 months.
No. 3. 5-11 months. No. to. 4-8 months.
No. 4. 5-8 months. No. 11. 7-8 months.
No. 5. 5-7 months. No. 12. 4-6 months.
No. 6. 3-5 months. No. 13. 18-19 months.

The behavior of all but 11 and 13 was practically the same.
When put into the box the cat would show evident signs of
discomfort and of an impulse to escape from confinement.
It tries to squeeze through any opening; it claws and bites
at the bars or wire; it thrusts its paws out through any
opening and claws at everything it reaches; it continues its
efforts when it strikes anything loose and shaky; it may
claw at things within the box. It does not pay very much
attention to the food outside, but seems simply to strive
instinctively to escape from confinement. The vigor with
which it struggles is extraordinary. For eight or ten
minutes it will claw and bite and squeeze incessantly.
With 13, an old cat, and 11, an uncommonly sluggish cat,
the behavior was different. They did not struggle vigor-
ously or continually. On some occasions they did not even
struggle at all. It was therefore necessary to let them out
of some box a few times, feeding them each time. After
they thus associate climbing out of the box with getting
food, they will try to get out whenever putin. They do not,
even then, struggle so vigorously or get so excited as the
rest. In either case, whether the impulse to struggle be

36 Animal Intelligence

due to an instinctive reaction to confinement or to an asso-
ciation, it is likely to succeed in letting the cat out of the
box. The cat that is clawing all over the box in her impul-
sive struggle will probably claw the string or loop or button
so as to open the door. And gradually all the other non-
successful impulses will be stamped out and the particular
impulse leading to the successful act will be stamped in by
the resulting pleasure, until, after many trials, the cat will,
when put in the box, immediately claw the button or loop
in a definite way.

The starting point for the formation of any association
in these cases, then, is the set of instinctive activities which
are aroused when a cat feels discomfort in the box either
because of confinement or a desire for food. This discom-
fort, plus the sense-impression of a surrounding, confining
wall, expresses itself, prior to any experience, in squeezings,
clawings, bitings, etc. From among these movements one
is selected by success. But this is the starting point only
in the case of the first box experienced. After that the cat
has associated with the feeling of confinement certain im-
pulses which have led to success more than others and are
thereby strengthened. A cat that has learned to escape
from A by clawing has, when put into C or G, a greater ten-
dency to claw at things than it instinctively had at the start,
and a less tendency to squeeze through holes. A very
pleasant form of this decrease in instinctive impulses was
noticed in the gradual cessation of howling and mewing.
However, the useless instinctive impulses die out slowly,
and often play an important part even after the cat has had
experience with six or eight boxes. And what is important
in our previous statement, namely, that the activity of an
animal when first put into a new box is not directed by any
appreciation of that box’s character, but by certain general

Experimental Study of Associative Processes 37

impulses to act, is not affected by this modification. Most
of this activity is determined by heredity; some of it, by
previous experience.

My use of the words instinctive and impulse may cause ~
some misunderstanding unless explained here. Let us,
throughout this book, understand by instinct any reaction
which an animal makes to a situation without experience.
It thus includes unconscious as well as conscious acts.
Any reaction, then, to totally new phenomena, when first
experienced, will be called instinctive. Any impulse then
felt will be called an instinctive impulse. Instincts include
whatever the nervous system of an animal, as far as inher-
ited, is capable of. My use of the word will, I hope, every-
where make clear what fact I mean. If the reader gets the
fact meant in mind it does not in the least matter whether
he would himself call such a fact instinct or not. Any
one who objects to the word may substitute ‘hocus-pocus’
for it wherever it occurs. The definition here made will not
be used to prove or disprove any theory, but simply as a
signal for the reader to imagine a certain sort of fact.

The word impulse is used against the writer’s will, but
there is no better. Its meaning will probably become clear
as the reader finds it in actual use, but to avoid misconcep-
tion at any time I will state now that impulse means the
consciousness accompanying a muscular innervation apart
from that feeling of the act which comes from seeing oneself
move, from feeling one’s body in a different position, etc. It
is the direct feeling of the doing as distinguished from the
idea of the act done gained through eye, etc. For this
reason I say ‘impulse and act’ instead of simply ‘act.’
Above all, it must be borne in mind that by impulse I never
mean the motive to the act. In popular speech you may say
that hunger is the impulse which makes the cat claw. That

38 Animal Intelligence

will never be the use here. The word motive will always
denote that sort of consciousness. Any one who thinks
that the act ought not to be thus subdivided into impulse
and deed may feel free to use the word act for impulse or 1m-
pulse and act throughout, if he will remember that the act
in this aspect of being felt as to be done or as doing is in
animals the important thing, is the thing which gets asso-
ciated, while the act as done, as viewed from outside, is a
secondary affair. I prefer to have a separate word, zmpulse,
for the former, and keep the word act for the latter, which it
commonly means.

Starting, then, with its store of instinctive impulses,
the cat hits upon the successful movement, and gradually
associates it with the sense-impression of the interior of the
box until the connection is perfect, so that it performs the
act as soon as confronted with the sense-impression. The
formation of each association may be represented graphi-
cally by a time-curve. In these curves lengths of one milli-
meter along the abscissa represent successive experiences
in the box, and heights of one millimeter above it each
represent ten seconds of time. The curve is formed by
joining the tops of perpendiculars erected along the abscissa
r mm. apart (the first perpendicular coinciding with the y
line), each perpendicular representing the time the cat was
in the box before escaping. Thus, in Fig. 2 on page 39 the
curve marked z2 im A shows that, in 24 experiences or
trials in box A, cat 12 took the following times to perform
the act, 160 sec., 30 sec., go Sec., 60, 15, 28, 20, 30, 22, 11, 15,
20, 12, 10, 14, 10, 8, 8, 5, 10, 8, 6,6, 7. Ashort vertical line
below the abscissa denotes that an interval of approximately
24 hours elapsed before the next trial. Where the interval
was longer it is designated by a figure 2 for two days, 3 for
three days, etc. If the interval was shorter, the number of

Experimental Study of Associative Processes 39

[AS ==
SoS >
{3inA.
A.
a
1O0inA. 74
Average in A.
[r=
linA.

IG 25

40 Animal Intelligence

hours is specified by 1 hr., 2 hrs., etc. In many cases the
animal failed in some trial to perform the act in ten or
fifteen minutes and was then taken out by me. Such fail-
ures are denoted by a break in the curve either at its start
or along its course. In some cases there are short curves
after the main ones. These, as shown by the figures be-
neath, represent the animal’s mastery of the association
after a very long interval of time, and may be called memory-
curves. A discussion of them will come in the last part of
the chapter.

The time-curve is obviously a fair representation of the
progress of the formation of the association, for the two
essential factors in the latter are the disappearance of all
activity save the particular sort which brings success with
it, and perfection of that particular sort of act so that itis
done precisely and at will. Of these the second is, on deeper
analysis, found to be a part of the first; any clawing at a
loop except the particular claw which depresses it is theoreti-
cally a useless activity. If we stick to the looser phraseology,
however, no harm will be done. The combination of these
two factors is inversely proportional to the time taken,
provided the animal surely wants to get out at once. This
was rendered almost certain by the degree of hunger.
Theoretically a perfect association is formed when both
factors are perfect, — when the animal, for example, does
nothing but claw at the loop, and claws at it in the most
useful way for the purpose. In some cases (e.g. 2 in K on
page 53) neither factor ever gets perfected in a great many
trials. In some cases the first factor does but the second
does not, and the cat goes at the thing not always in the
desirable way. In all cases there is a fraction of the time
which represents getting oneself together after being
dropped in the box, and realizing where one is. But for

ISinC

e

42 Animal Intelligence

our purpose all these matters count little, and we may take
the general slope of the curve as representing very fairly
the progress of the association. The slope of any particular
part of it may be due to accident. Thus, very often the
second experience may have a higher time-point than the
first, because the first few successes may all be entirely
due to accidentally hitting the loop, or whatever it is, and
whether the accident will happen sooner in one trial than
another is then a matter of chance. Considering the general
slope, it is, of course, apparent that a gradual descent — say,
from initial times of 300 sec. to a constant time of 6 or 8 sec.
in the course of 20 to. 30 trials —represents a difficult
association; while an abrupt descent, say in 5 trials, from a
similar initial height, represents a very easy association.
Thus, 2 in Z, on page 57, is a hard,and 1 in I, on page 4g,
an easy association.

In boxes A, C, D, E, I, 100 per cent of the cats given a
chance to do so, hit upon the movement and formed the
association. The following table shows the results where
some cats failed: —

TABLE I

No. Cats TrieEp No. Cats FAILED

Ae OO sy
anno on
bo NH KN

The time-curves follow. By referring to the description
of apparatus they will be easily understood. Each mm.
along the abscissa represents one trial. Each mm. above
it represents ro seconds.

These time-curves show, in the first place, what associa-

Experimental Study of Associative Processes

43

——<—a—e—eaeoeoT
1OinD
I2inD
Ve \
HinD 4inD Average inD

ItinC
FIG. 4.

44 Animal Intelligence

tions are easy for an animal to form, and what are hard.
The act must be one which the animal will perform in the
course of the activity which its inherited equipment incites
or its previous experience has connected with the sense-
impression of a box’s interior. The oftener the act nat-

2ink. 14 GinE 14 SinE 14 SimE 20.
Fic. 5;

urally occurs in the course of such activity, the sooner it
will be performed in the first trial or so, and this is one con-
dition, sometimes, of the ease of forming the association.
For if the first few successes are five minutes apart, the
influence of one may nearly wear off before the next, while
if they are forty seconds apart the influences may get sum-
mated. But this is not the only or the main condition of
the celerity with which an association may be formed. It
depends also on the amount of attention given to the act.
An act of the sort likely to be well attended to will be learned

Experimental Siudy of Associative Processes 45

4inf. 4.

30.
3 i nG. Memory.

7 A
2

3nG. 2
Fic. 6,

46 Animal Intelligence

more quickly. Here, too, accident may play a part, for a
cat may merely happen to be attending to its paw when it
claws. ‘The kind of acts which insure attention are those
where the movement which works the mechanism is one
which the cat makes definitely to get out. Thus A (O at
front) is easier to learn than C (button), because the cat
does A in trying to claw down the front of the box and so
is attending to what it does; whereas it does C generally
in a vague scramble along the front or while trying to claw
outside with the other paw, and so does not attend to the
little unimportant part of its act which turns the button
round. Above all, simplicity and definiteness in the act
make the association easy. G (thumb latch), J (double)
and K and L (triples) are hard, because complex. E is
easy, because directly in the line of the instinctive im-
pulse to try to pull oneself out of the box by clawing at
anything outside. It is thus very closely attended to.
The extreme of ease is reached when a single experience
stamps the association in so completely that ever after the
act is done at once. This is approached in I and E.

In these experiments the sense-impressions offered no
difficulty one more than the other.

Vigor, abundance of movements, was observed to make
differences between individuals in the same association.
It works by shortening the first times, the times when the
cat still does the act largely by accident. Nos. 3 and 4
show this throughout. Attention, often correlated with lack
of vigor, makes a cat form an association more quickly after
he gets started. No. 13 shows this somewhat. The ab-
sence of a fury of activity let him be more conscious of what
he did do.

The curves on pages 57 and 58, showing the history of
cats 1, 5, 13 and 3, which were let out of the box Z when

Experimental Study of Associative Processes 47

~ 4
2 al
4inG. Memory.

4inG. 2 D) Oh.

Do iio
4in tt.
as vas eae er
{Oinf 72.
ar a gid "ag al Miers! te
p 34 29.3°0 Hint. 12inH.
Sink. 5inH

48 Animal Intelligence

they licked themselves, and of cats 6, 2 and 4, which were
let out when they scratched themselves, are interesting be-
cause they show associations where there is no congruity
(no more to a cat than to a man) between the act and the
result. One chick, too, was thus freed whenever he pecked
at his feathers to dress them. He formed the association,
and would whirl his head round and poke it into his feathers
as soon as dropped in the box. There is in all these cases
a noticeable tendency, of the cause of which I am ignorant,
to diminish the act until it becomes a mere vestige of a
lick or scratch. After the cat gets so that it performs the
act soon after being put in, it begins to do it less and less
vigorously. The licking degenerates into a mere quick
turn of the head with one or two motions up and down with
tongue extended. Instead of a hearty scratch, the cat
waves its paw up and down rapidly for an instant. More-
over, if sometimes you do not let the cat out after this
feeble reaction, it does not at once repeat the movement,
as it would do if it depressed a thumb piece, for instance,
without success in getting the door open. Of the reason for
this difference I am again ignorant.

Previous experience makes a difference in the quickness
with which the cat forms the associations. After getting
out of six or eight boxes by different sorts of acts the cat’s
general tendency to claw at loose objects within the box is
strengthened and its tendency to squeeze through holes
and bite bars is weakened ; accordingly it will learn associa-
tions along the general line of the old more quickly. Fur-
ther, its tendency to pay attention to what it is doing gets
strengthened, and this is something which may properly
be called a change in degree of intelligence. A test was
made of the influence of experience in this latter way by
putting two groups of cats through I (lever), one group

Experimental Study of Associative Processes 49

im J dinl 2

Sin] 2
30
3inl
a eae "CO Git Pea Pa ae aaa aac a
Ilin] I2in] On T,

50 Animal Intelligence

(1, 2, 3, 4, 5) after considerable experience, the other (10,
11, 12) after experience with only one box. As the act in I
was not along the line of the acts in previous boxes, and as
a decrease in the squeezings and bitings would be of little
use in the box as arranged, the influence of experience in
the former way was of little account. The curves of all
are shown on page 49.

If the whole set of curves are examined in connection with
the following table, which gives the general order in which
each animal took up the different associations which he
eventually formed, many suggestions of the influence of
experience will be met with. The results are not exhaustive
enough to justify more than the general conclusion that
there is such an influence. By taking more individuals
and thus eliminating all other factors besides experience,
one can easily show just how and how far experience facili-
tates association.

When, in this table, the letters designating the boxes are
in italics it means that, though the cat formed the associa-
tion, it was in connection with other experiments and so is
not recorded in the curves.

TABLE II

a

HNOHYOA
Navan S
gael: Ne ie Fa |
mom N
|
Ss =
AA

> >
OmmA
NOOO

ale ese

A
Cc
A
Cc
C
A
A
C
S
C
A

© En hoe ge Be ee poe co Pic el a hl he

oa
VY -

QinJ. 3

"4ind. a a

SinJ. 4 3 2
FIG. 9.

52 Animal Intelligence

The advantage due to experience in our experiments is
not, however, the same as ordinarily in the case of trained
animals. With them the associations are with the acts or
voice of man or with sense-impressions to which they natu-
rally do not attend (e.g. figures on a blackboard, ringing of
a bell, some act of another animal). Here the advantage
of experience is mainly due to the fact that by such ex-
perience the animals gain the habit of attending to the
master’s face and voice and acts and to sense-impressions
in general.

I made no attempt to find the differences in ability to
acquire associations due to age or sex or fatigue or circum-
stances of any sort. By simply finding the average slope
in the different cases to be compared, one can easily demon-
strate any such differences that exist. So far as this dis-
covery is profitable, investigation along this line ought now
to go on without delay, the method being made clear.
Of differences due to differences in the species, genus, etc.,
of the animals I will speak after reviewing the time-curves
of dogs and chicks.

In the present state of animal psychology there is another
value to these results which was especially aimed at by the in-
vestigator from the start. They furnish a quantitative esti-
mate of what the average cat can do, so that if any one has an
animal which he thinks has shown superior intelligence or
perhaps reasoning power, he may test his observations and
opinion by taking the time-curves of the animal in such
boxes as I have described.

If his animal in a number of cases forms the associations
very much more quickly, or deals with the situation in a
more intelligent fashion than my cats did, then he may have
ground for claiming in his individual a variation toward
greater intelligence and, possibly, intelligence of a different

Experimental Study of Associative Processes 53

aml.

4inKk

rales
3h th, th.

FIG Io;

54 Animal Intelligence

order. On the other hand, if the animal fails to rise above
the type in his dealings with the boxes, the observer should
confess that his opinion of the animal’s intelligence may
have been at fault and should look for a correction of it.

We have in these time-curves a fairly adequate measure
of what the ordinary cat can do, and how it does it, and in
similar curves soon to be presented a less adequate measure
of what a dog may do. If other investigators, especially
all amateurs who are interested in animal intelligence, will
take other cats and dogs, especially those supposed by own-
ers to be extraordinarily intelligent, and experiment with
them in this way, we shall soon get a notion of how much
variation there is among animals in the direction of more or
superior intelligence. The beginning here made is meager
but solid. The knowledge it gives needs to be much ex-
tended. The variations found in individuals should be
correlated, not merely with supposed superiority in intel-
ligence, a factor too vague to be very serviceable, but with
observed differences in vigor, attention, memory and muscu-
lar skill. No phenomena are more capable of exact and
thorough investigation by experiment than the associations
of animal consciousness. Never will you get a better
psychological subject than a hungry cat. When the crude
beginnings of this research have been improved and re-
placed by more ingenious and adroit experimenters, the
results ought to be very valuable.

Surely every one must agree that no man now has a right
to advance theories about what is in animals’ minds or to
deny previous theories unless he supports his thesis by
systematic and extended experiments. My own theories,
soon to be proclaimed, will doubtless be opposed by many.
I sincerely hope they will, provided the denial is accompa-
nied by actual experimental work. In fact, I shall be tempted

ed Qs
Sink
Sink, continued = ie
| = aie

70.
ee Ne AN 2

lOmL. fh. 9, x

56 Animal Intelligence

again and again in the course of this book to defend some
theory, dubious enough to my own mind, in the hope of
thereby inducing some one to oppose me and in opposing
me to make the experiments I have myself had no oppor-
tunity to make yet. Probably there will be enough op-
position if I confine myself to the theories I feel sure of.

EXPERIMENTS WITH Docs

The boxes used were as follows:

AA was similar to A (O at front), except that the loop was
of stiff cord § inch in diameter and was larger (33 inches
diameter); also it was hung a foot from the floor and 8
inches to the right of the door. ‘The box itself was 41 X 20
oe 23:

BB was similar to B, the loop being the same as in AA,
and being hung a foot from the floor. The box was of the
same size and shape as AA.

BBr was like BB, but the loop was hung 18 inches from
the floor.

CC was similar to C (button), but the button was 6
inches long, and the box was 36% X 22 X 23.

II was similar to I, but the box was 30 X 20 X 25 inches;
the door (11 inches wide, 6 high) was in the left front corner,
and the lever was 6 inches long and entered the box at a
point 2 inches to the right of the door and 4 inches above
the floor.

In M the same box as in II was used, but instead of a
lever projecting inside the box, a lever running outside
parallel to the plane of the front of the box and 18 inches
long was used. ‘This lay close against the bars compos-
ing the front of the box, and could be pawed down by
sticking the paw out an inch or so between two bars, at

58 Animal Intelligence

a point about 15 inches high and 6 inches in from the
right edge of the front. We may call M ‘Lever outside.’

SinZ

Sin Z. ]).

GinZ 2

Fic. 13.

N was a pen 5X3 feet made of wire netting 46 inches
high. ‘The door, 31 X 20, was in the right half of the front.
A string from the bolt passed up over a pulley and back to
the back center, where it was fastened 33 inches above the
floor. Biting or pawing this string opened the door.

Experimental Study of Associative Processes 59

O was like K, except that there was only one bar, that
the string ran inside the box, so that it was easily accessible,
and that the bolt raised in K by depression of the platform
could be raised in O (and was by the dog experimented on)
by sticking the muzzle out between two bars just above
the bolt and by biting the string, at the same time jerking
it upward. O was 30 X 20X 25 In size.

The box G was used for both dogs and cats, without any
variation save that for dogs the resistance of the door to
pressure outwards was doubled.

In these boxes were put in the course of the experiments
dog 1 (about 8 months old), and dogs 2 and 3, adults, all
of small size.

A dog who, when hungry, is shut up in one of these boxes
is not nearly so vigorous in his struggles to get out as is the
young cat. And even after he has experienced the pleasure
of eating on escape many times he does not try to get out
so hard as a cat, young or old. He does try to a certain
extent. He paws or bites the bars or screening, and tries
to squeeze out in a tame sort of way. He gives up his
attempts sooner than the cat, if they prove unsuccessful.
Furthermore his attention is taken by the food, not the
confinement. He wants to get fo the food, not out of the
box. So, unlike the cat, he confines his efforts to the front
of the box. It was also a practical necessity that the dogs
should be kept from howling in the evening, and for this
reason I could not use as motive the utter hunger which
the cats were made to suffer. In the morning, when the
experiments were made, the dogs were surely hungry,
and no experiment is recorded in which the dog was not
in a state to be willing to make a great effort for a bit of
meat, but the motive may not have been even and equal
throughout, as it was with the cats.

Fic. 14.

anAA.

Experimental Study of Associative Processes 61

The curves on page 60 are to be interpreted in the same
way as those for the cats, and are on the same scale. The
order in which No. 1 took up the various associations was
heb, BBr, \G, IN, CC) IF O-

The percentage of dogs succeeding in the various boxes
is given below, but is of no consequence, because so few
were tried, and because the motive, hunger, was not perhaps
strong enough, or equal in all cases.

In AA 3 out of 3.

In BB 0 out of 2 (that is, without previous experience
of AA).

In CC 2 out.ot: 2.

In IT 3 out of 3.

In M 1 out of 2.

In N 1 out of 3.

In Gt out of 3.

EXPERIMENTS WITH CHICKS

The apparatus was as follows:
P was simply a small pen arranged with two exits, one
leading to the inclosure where were the other chicks and

fp V2

FIG. 15. Fic. 16. Fic. 17.

food, one leading to another pen with no exit. The draw-
ing (Fig. 15 on this page) explains itself. A chick was

62 Animal Intelligence

placed at A and left to find its way out. The walls were
made of books stuck up on end.

Q was a similar pen arranged so that the real exit was
harder to find. (See Fig. 16.)

R was still another pen similarly constructed, with four
possible avenues to be taken. (See Fig. 17.)

S was a pen with walls 11 inches high. On the right side
an inclined plane of wire screening led from the floor of the
pen to the top of its front wall. Thence the chick could
jump down to where its fellows and the food and drink
were. S was 17X14 in size.

T was a pen of the same size as S, with a block of wood 3
inches by 3 and 2 inches high in the right back corner.
From this an inclined plane led to the top of the front wail
(on the right side of the box). But a partition was placed
along the left edge of this plane, so that a chick could reach
it only va the wooden block, not by a direct jump.

U was a pen 16X14xX10 inches. Along the back
toward the right corner were placed a series of steps 14
inches wide, the first 1, the second 2, and the third 3 inches
high. In the corner was a platform 4X4, and 4 high, from
which access to the top of the front wall of the pen could
be gained by scrambling up inside a stovepipe 11 inches
long, inclined upward at an angle of about 30°. From
the edge of the wall the chick could, of course, jump down to
food and society. The top of the pen was covered so that
the chick could not from the platform jump onto the edge
of the stovepipe or the top of the pen wall. The only
means of exit was to go up the steps to the platform, up
through the stovepipe to the front wall, and then jump
down.

The time-curves for chicks 90, 91, 92, 93, 94 and 95, all
2-8 days old when experimented on, follow on page 65.

Experimental Study of Associative Processes 63

The scale is the same as that in the curves of the cats and
dogs. Besides these simple acts, which any average chick
will accidentally hit upon and associate, there are, in the
records of my preliminary study of animal intelligence,
a multitude of all sorts of associations which some chicks
have happened toform. Chicks have escaped from confine-
ment by stepping on a little platform in the back of the box,
by jumping up and pulling a string like that in D, by peck-
ing at a door, by climbing up a spiral staircase and out
through a hole in the wall, by doing this and then in ad-
dition walking across a ladder for a foot to another wall
from which they jump down, etc. Not every chick will
happen upon the right way in these cases, but the chicks
who did happen upon it all formed the associations perfectly
after enough trials.

The behavior of the chicks shows the same general charac-
ter as that of the cats, conditioned, of course, by the different
nature of the instinctive impulses. ‘Take a chick put in T
(inclined plane) for an example. When taken from the food
and other chicks and dropped into the pen he shows evident
signs of discomfort; he runs back and forth, peeping loudly,
trying to squeeze through any openings there may be,
jumping up to get over the wall, and pecking at the bars
or screen, if such separate him from the other chicks.
Finally, in his general running around he goes up the inclined
plane a way. He may come down again, or he may go on
up far enough to see over the top of the wall. If he does,
he will probably go running up the rest of the way and jump
down. With further trials he gains more and more of an
impulse to walk up an inclined plane when he sees it, while
the vain running and pecking, etc., are stamped out by the
absence of any sequent pleasure. Finally, the chick goes
up the plane as soon as put in. In scientific terms this

64 Animal Intelligence

history means that the chick, when confronted by loneliness
and confining walls, responds by those acts which in similar
conditions in nature would be likely to free him. Some one
of these acts leads him to the successful act, and the result-
ing pleasure stamps it in. Absence of pleasure stamps all
others out. The case is just the same as with dogs and cats.
The time-curves are shown in Fig. 18.

Coming now to the question of differences in intelligence
between the different animals, it is clear that such differ-
ences are hard to estimate accurately. The chicks are
surely very much slower in forming associations and less
able to tackle hard ones, but the biggest part of the differ-
ence between what they do and what the dogs and cats do
is not referable so much to any difference in intelligence as to
a difference in their bodily organs and instinctive impulses.
As between dogs and cats, the influence of the difference
in quantity of activity, in the direction of the instinctive
impulses, in the versatility of the fore limb, is hard to
separate from the influence of intelligence proper. The
best practical tests to judge such differences in general
would be differences in memory, which are very easily got
at, differences in the delicacy and complexity attainable,
and, of course, differences in the slope of the curves for the
same association. If all these tests agreed, we should have
a right to rank one animal above the other in a scale of
intelligence. But this whole question of grading is, after
all, not so important for comparative psychology as its
popularity could lead one to think. Comparative psy-
chology wants first of all to trace human intellection back
through the phylum to its origin, and in this aim is helped
little by knowing that dogs are brighter than cats, or
whales than seals, or horses than cows. Further, the whole
question of ‘intelligence’ should be resolved into particular

Experimental Study of Associative Processes 65

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66 Animal Intelligence

inquiries into the development of attention, activity,
memory, etc.

So far as concerns dogs and cats, I should decide that
the former were more generally intelligent. The main
reason, however, why dogs seem to us so intelligent is not
a good reason for the belief. It is because, more than any
other domestic animal, they direct their attention to us, to
what we do, and so form associations connected with acts
of ours.

Having finished our attempt to give a true description of
the facts of association, so far as observed from the outside,
we may now progress to discuss its inner nature. A little
preface about certain verbal usages is necessary before doing
so. Throughout I shall use the word ‘animal’ or ‘animals,’
and the reader might fancy that I took it for granted that
the associative processes were the same in all animals as
in these cats and dogs of mine. Really, I claim for my
animal psychology only that it is the psychology of just
these particular animals. What this warrants about ani-
mals in general may be left largely to the discretion of
the reader. As I shall later say, it is probable that in re-
gard to imitation and the power of forming associations
from a lot of free ideas, the anthropoid primates are es-
sentially different from the cats and dogs.

The reasons why I say ‘animals’ instead of ‘dogs and
cats of certain ages’ are two. I do think that the probabil-
ity that the other mammals, barring the primates, offer no
objections to the theories here advanced about dogs and
cats is a very strong probability, strong enough to force
the burden of proof upon any one who should, for instance,
say that horse-goat psychology was not like cat-dog psy-
chology in these general matters. I should claim that,
till the contrary was shown in any case, my statements

Experimental Study of Associative Processes 67

should stand for the mammalian mind in general, barring the
primates. My second reason is that I hate to burden the
reader with the disgusting rhetoric which would result if
I had to insert particularizations and reservations at every
step. The word ‘animal’ is too useful, rhetorically, to be
sacrificed. Finally, masmuch as most of my theorizing
will be in the line of denying certain relatively high functions
to animals, the evidence from cats and dogs is sufficient,
for they are from among the most intelligent animals, and
functions of the kind to be discussed, if absent in their
case, are probably absent from the others.

REASONING OR INFERENCE

The first great question is whether or not animals are ever
led to do any of their acts by reasoning. Do they ever con-
clude from inference that a certain act will produce a certain
desired result,and sodoit? The best opinion has been that
they do not. The best interpretation of even the most
extraordinary performances of animals has been that they
were the result of accident and association or imitation.
But it has after all been only opinion and interpretation,
and the opposite theory persistently reappears in the litera-
ture of the subject. So, although it is in a way superfluous to
give the coup de grace to the despised theory that animals
reason, I think it is worth while to settle this question once
for all.

The great support of those who do claim for animals the
ability to infer has been their wonderful performances which
resemble our own. These could not, they claim, have hap-
pened by accident. Noanimal could learn to open a latched
gate by accident. The whole substance of the argument
vanishes if, as a matter of fact, animals do learn those things

68 Animal Intelligence

by accident. They certainly do.. In this investigation
choice was made of the intelligent performances described
by Romanes in the following passages. I shall quote at
some length because these passages give an admirable
illustration of an attitude of investigation which this re-
search will, I hope, render impossible for any scientist in
the future. Speaking of the general intelligence of cats,
Romanes says:

“Thus, for instance, while I have only heard of one solitary
case . . . of a dog which, without tuition, divined the use of a
thumb latch so as to open a closed door by jumping on the handle
and depressing the thumb-piece, I have received some half-
dozen instances of this display of intelligence on the part of
cats. These instances are all such precise repetitions of one
another that I conclude the fact to be one of tolerably ordinary
occurrence among cats, while it is certainly rare among dogs.
I may add that my own coachman once had a cat which, cer-
tainly without tuition, learnt thus to open a door that led into
the stables from a yard into which looked some of the windows
of the house. Standing at these windows when the cat did not
see me, I have many times witnessed her modus operandt.
Walking up to the door with a most matter-of-course kind of air,
she used to spring at the half hoop handle just below the thumb
latch. Holding on to the bottom of this half-hoop with one
fore paw, she then raised the other to the thumb piece, and
while depressing the latter finally with her hind legs scratched
and pushed the door posts so as to open the door... .

“Of course in all such cases the cats must have previously
observed that the doors are opened by persons placing their
hands upon the handles and, having observed this, the animals
act by what may be strictly termed rational imitation. But
it should be observed that the process as a whole is something
more than imitative. For not only would observation alone be
scarcely enough (within any limits of thoughtful reflection that

Experimental Study of Associative Processes 69

it would be reasonable to ascribe to an animal) to enable a cat
upon the ground to distinguish that the essential part of the
process consists not in grasping the handle, but in depressing
the latch; but the cat certainly never saw any one, after having
depressed the latch, pushing the door posts with his legs; and
that this pushing action is due to an originally deliberate inten-
tion of opening the door, and not to having accidentally found
this action to assist the process, is shown by one of the cases
communicated to me; for in this case, my correspondent says,
‘the door was not a loose-fitting one, by any means, and I was
surprised that by the force of one hind leg she should have been
able to push it open after unlatching it.’ Hence we can only
conclude that the cats in such cases have a very definite idea as
to the mechanical properties of a door: they know that to make
it open, even when unlatched, it requires to be pushed — a very
different thing from trying to imitate any particular action which
they may see to be performed for the same purpose by man.
The whole psychological process, therefore, implied by the fact
of a cat opening a door in this way is really most complex.
First the animal must have observed that the door is opened by
the hand grasping the handle and moving the latch. Next she
must reason, by ‘the logic of feelings’ — ‘If a hand can do it,
why not a paw?’ Then strongly moved by this idea she makes
the first trial. The steps which follow have not been observed,
so we cannot certainly say whether she learns by a succession
of trials that depression of the thumb piece constitutes the
essential part of the process, or, perhaps more probably, that her
initial observations supplied her with the idea of clicking the
thumb piece. But, however this may be, it is certain that the
pushing with the hind feet after depressing the latch must
be due to adaptive reasoning unassisted by observation; and
only by the concerted action of all her limbs in the perform-
ance of a highly complex and most unnatural movement is
her final purpose attained.” (Animal Intelligence, pp. 420-
422.)

7O Animal Intelligence

A page or two later we find a less ponderous account of
a cat’s success in turning aside a button and so opening a
window : —

“At Parara, the residence of Parker Bowman, Esq., a full-
grown cat was one day accidentally locked up in a room without
any other outlet than a small window, moving on hinges, and
kept shut by means of a swivel. Not long afterwards the win-
dow was found open and the cat gone. This having happened
several times, it was at last found that the cat jumped upon the
window sill, placed her fore paws as high as she could reach
against the side, deliberately reached with one over to the
swivel, moved it from its horizontal to a vertical position, and
then, leaning with her whole weight against the window, swung
it open and escaped.” (Animal Intelligence, p. 425.)

A description has already been given on page 31 of the
small box (C), whose door fell open when the button was
turned, and also of a large box (CC) for the dogs, with a
similar door. The thumb-latch experiment was carried
on with the same box (G) for both cats and dogs, but the
door was arranged so that a greater force (1.3 kilograms)
was required in the case of the dogs. It will be remembered
that the latch was so fixed that if the thumb piece were
pressed down, without contemporaneous outward pressure
of the door, the latch bar would merely drop back into its
catch as soon as the paw was taken off the door. IH, how-
ever, the door were pushed outward, the latch bar, being
pressed closely against the outer edge of its catch, would,
if lifted, be likely to fall outside it and so permit the door
to open if then or later sufficient pressure were exerted.
Fight cats (Nos. 1, 2, 3, 4, 5, 6, 7 and 13) were, one at a time,
left in this thumb-latch box. All exhibited the customary
instinctive clawings and squeezings and bitings. Out of
the eight all succeeded in the course of their vigorous

Experimental Study of Associative Processes 71

struggles in pressing down the thumb piece, so that if the
door had been free to swing open, they could have escaped.
Six succeeded in pushing both thumb-piece down and door
out, so that the bar did not fall back into its place. Of
these five succeeded in also later pushing the door open,
so that they escaped and got the fish
outside. Of these, three, after re-
peated trials, associated the com-
plicated movements required with
the sight of the interior of the box so
firmly that they attacked the thumb
latch the moment they were put in.
The history of the formation of the
association in the case of 3 and of 4 is
shown in the curves in Figs. 6 and 7.
In the case of 13 the exact times were
not taken. The combination of ac-
cidents required was enough to make
No. 1 and No. 6 take a long time
to get out. Consequently, weariness
and failure inhibited their impulses
to claw, climb, etc., more than the
rare pleasure from getting out
strengthened them, and they failed
to form the association. Like the
cats who utterly failed to get out, they finally ceased
to try when put in. The history of their efforts is as in
Table 3: the figures in the columns represent the time (in
minutes and seconds) the animal was in the box before
escaping or before being taken out if he failed to es-
cape. Cases of failure are designated by an F after the
figures. Double lines represent an interval of twenty-four
hours.

TABLE 3

72 Animal Intelligence

It should be noted that, although cats 3 and 4 had had
some experience in getting out of boxes by clawing at loops
and turning buttons, they had never had anything at all
like a thumb latch to claw at, nor had they ever seen the
door opened by its use, nor did they even have any experi-
ence of the fact that the part of the box where the thumb
piece was was the door. And we may insert here, what
will be stated more fully later, that there was displayed
no observation of the surroundings or deliberation upon
them. It was just a mad scramble to get out.

Three dogs (1, 2 and 3) were given a chance to liberate
themselves from this same box. 2 and 3, who were rather
inactive, failed to even push the thumb piece down. No. 1,
who was very active, did push it down at the same time
that she happened to be pushing against the door. She
repeated this and formed the association as shown in the
curve on page 60. She had had experience only of es-
caping by pulling a loop of string.

Out of 6 cats who were put in the box whose door opened
by a button, not one failed, in the course of its impulsive
activity, to push the button around. Sometimes it was
clawed to one side from below; sometimes vigorous pressure
on the top turned it around; sometimes it was pushed up
by the nose. No cat who was given repeated trials failed
to form a perfect association between the sight of the in-
terior of that box and the proper movements. Some of
these cats had been in other boxes where pulling a loop of
string liberated them, 3 and 4 had had considerable experi-
ence with the boxes and probably had acquired a general
tendency to claw at loose objects. 10, 11 and 12 had never
been in any box before. The curves are on pages 41 and 43.

Of two dogs, one, when placed in a similar but larger
box, succeeded in hitting the button in such a way as to let

Experimental Study of Associative Processes 73

the door open, and formed a permanent association, as
shown by the curves on page 41. Noone who had seen the
behavior of these animals when trying to escape could
doubt that their actions were directed by instinctive im-
pulses, not by rational observation. It is then absolutely
sure that a dog or cat can open a door closed by a thumb
latch or button, merely by the accidental success of its
natural impulses. If a// cats, when hungry and in a small
box, will accidentally push the button that holds the door,
an occasional cat in a large room may very well do the same.
If three cats out of eight will accidentally press down a
thumb piece and push open a small door, three cats out of
a thousand may very well open doors or gates in the same
way.

But besides thus depriving of their value the facts which
these theorizers offer as evidence, we may, by a careful
examination of the method of formation of these associations
as it is shown in the time-curves, gain positive evidence that
no power of inference was present in the subjects of the ex-
periments. Surely if 1 and 6 had possessed any power of
inference, they would not have failed to get out after having
done so several times. Yet they did. (See p.71.) If they
had once even, much less if they had six or eight times,
inferred what was to be done, they should have made the
inference the seventh or ninth time. And if there were in
these animals any power of inference, however rudimentary,
however sporadic, however dim, there should have appeared
among the multitude some cases where an animal, seeing
through the situation, knows the proper act, does it, and
from then on does it immediately upon being confronted
with the situation. There ought, that is, to be a sudden -
vertical descent in the time-curve. Of course, where the
act resulting from the impulse is very simple, very obvious,

74 Animal Intelligence

and very clearly defined, a single experience may make the
association perfect, and we may have an abrupt descent
in the time-curve without needing to suppose inference.
But if in a complex act, a series of acts or an ill-defined act,
one found such a sudden consummation in the associative
process, one might very well claim that reason was at work.
Now, the scores of cases recorded show no such phenomena.
The cat does not look over the situation, much less think it
over, and then decide what to do. It bursts out at once
into the activities which instinct and experience have
settled on as suitable reactions to the situation ‘confinement
when hungry with food outside.’ It does not ever in the
course of its successes realize that such an act brings food
and therefore decide to do it and thenceforth do it im-
mediately from decision instead of from impulse. The one
impulse, out of many accidental ones, which leads to pleas-
ure, becomes strengthened and stamped in thereby, and
more and more firmly associated with the sense-impression
of that box’s interior. Accordingly it is sooner and sooner
fulfilled. Futile impulses are gradually stamped out.
The gradual slope of the time-curve, then, shows the ab-
sence of reasoning. ‘They represent the wearing smooth of
a path in the brain, not the decisions of a rational conscious-
ness.

In a later discussion of imitation further evidence that
animals do not reason will appear. For the present, suffice
it to say, that a dog, or cat, or chick, who does not in his
own impulsive activity learn to escape from a box by pulling
the proper loop, or stepping on a platform, or pecking at a
door, will not learn it from seeing his fellows do so. They
are incapable of even the inference (if the process may be
dignified by that name) that what gives another food will
give it to them also. So, also, it will be later seen that an

Experimental Study of Associative Processes 75

animal cannot learn an act by being put through it. For
instance, a cat who fails to push down a thumb piece and
push out the door cannot be taught by having one take
its paw and press the thumb piece down with it. This
could be learned by a certain type of associative process
without inference. Were there inference, it surely would be
learned.

Finally, attention may be called to the curves which
show the way that the animal mind deals with a series
of acts (e.g. curves for G, J, K, L and O, found on pages 45
to 55 and 60.) Were there any reasoning the animals ought
early to master the method of escape in these cases (see
descriptions on pages 31 to 34) so as to do the several
acts in order, and not to repeat one after doing it once, or
else ought utterly to fail to master the thing. But, in all
these experiments, where there was every motive for the
use of any reasoning faculty, if such existed, where the ani-
mals literally lived by their intellectual powers, one finds
no sign of abstraction, or inference, or judgment.

So far I have only given facts which are quite uninfluenced
by any possible incompetence or prejudice of the observer.
These alone seem to disprove the existence of any rational
faculty in the subjects experimented on. I may add that
my observations of all the conduct of all these animals
during the months spent with them, failed to find any act
that even seemed due to reasoning. I should claim that this
quarrel ought now to be dropped for good and all,— that
investigation ought to be directed along more sensible and
profitable lines. I should claim that the psychologist who
studies dogs and cats in order to defend this ‘reason’ theory
is on a level with a zodlogist who should study fishes with
a view to supporting the thesis that they possessed clawed
digits. The rest of this account will deal with more prom-

76 Animal Intelligence

ising problems, of which the first, and not the least im-
portant, concerns the facts and theories of imitation.

IMITATION

To the question, ‘Do animals imitate?’ science has
uniformly answered, ‘Yes.’ But so long as the question
is left in this general form, no correct answer to it is possible.
It will be seen, from the results of numerous experiments
soon to be described, that imitation of a certain sort is
not possible for animals, and before entering upon that
description it will be helpful to differentiate this matter of
imitation into several varieties or aspects. The presence
of some sorts of imitation does not imply that of other
sorts.

There are, to begin with, the well-known phenomena
presented by the imitative birds. The power is extended
widely, ranging from the parrot who knows a hundred or
more articulate sounds to the sparrow whom a patient
shoemaker taught to get through a tune. Now, if a bird
really gets a sound in his mind from hearing it and sets out
forthwith to imitate it, as mocking birds are said at times to
do, it is a mystery and deserves closest study. If a bird,
out of a lot of random noises that it makes, chooses those
for repetition which are like sounds that he has heard, it
is again a mystery why, though not as in the previous case
a mystery how, he doesit. The important fact for our pur-
pose is that, though the imitation of sounds is so habitual,
there does not appear to be any marked general imitative
tendency in these birds. There is no proof that parrots do
muscular acts from having seen other parrots do them.
But this should be studied. At any rate, until we know
what sort of sounds birds imitate, what circumstances

Experimental Study of Associative Processes 77

or emotional attitudes these are connected with, how they
learn them and, above all, whether there is in birds which
repeat sounds any tendency to imitate in other lines, we
cannot, it seems to me, connect these phenomena with
anything found in the mammals or use them to advantage
in a discussion of animal imitation as the forerunner of
human. In what follows they will be left out of account,
will be regarded as a specialization removed from the general
course of mental development, just as the feathers or right
aortic arch of birds are particular specializations of no con-
sequence for the physical development of mammals. For
us, henceforth, imitation will mean imitation minus the
phenomena of imitative birds.

There are also certain pseudo-imitative or semi-imitative
phenomena which ought to be considered by themselves.
For example, the rapid loss of the fear of railroad trains or
telegraph wires among birds, the rapid acquisition of ar-
boreal habits among Australian rodents, the use of proper
feeding grounds, etc., may be held to be due to imitation.
The young animal stays with or follows its mother from a
specific instinct to keep near that particular object, to wit,
its mother. It may thus learn to stay near trains, or
scramble up trees, or feed at certain places and on certain
plants. Actions due to following pure and simple may thus
simulate imitation. Other groups of acts which now seem
truly imitative may be indirect fruits of some one instinct.
This must be kept in mind when one estimates the supposed
imitation of parents by young. Further, it is certain that
in the case of the chick, where early animal life has been
carefully observed, instinct and individual experience be-
tween them rob imitation of practically all its supposed in-
fluence. Chicks get along without a mother very well.
Yet no mother takes more care of her children than the

78 Animal Intelligence

hen. Care in other cases, then, need not mean instruction
through imitation. °

These considerations may prevent an unreserved accept-
ance of the common view that young animals get a great
number of their useful habits from imitation, but I do not
expect or desire them to lead to its summary rejection.
I should not now myself reject it, though I think it quite
possible that more investigation and experiment may
finally reduce all the phenomena of so-called imitation of
parents by young to the level of indirect results of instinctive
acts.

Another special department of imitation may be at least
vaguely marked off: namely, apparent imitation of certain
limited sorts of acts which are somewhat frequent in the
animal’s life. An example will do better than further
definition.

Some sheep were being driven on board ship one at a time.
In the course of their progress they had to jump over a
hurdle. On this being removed before all had passed it,
the next sheep was seen to jump as if to get over a hurdle,
and so on for five or six, apparently sure evidence that they
imitated the action, each of the one in front. Now, it is
again possible that among gregarious animals there may be
elaborate connections in the nervous system which allow
the sight of certain particular acts in another animal to
arouse the innervation leading to those acts, but that these
connections are limited. The reactions on this view are
specific responses to definite signals, comparable to any
other instinctive or associational reaction. The sheep
jumps when he sees the other sheep jump, not because of
a general ability to do what he sees done, but because he is
furnished with the instinct to jump at such a sight, or
because his experience of following the flock over boulders

Experimental Study of Associative Processes 79

and brooks and walls has got him into the habit of jumping
at the spot where he sees one ahead of him jump; and so
he jumps even though no obstacle be in his way. If due
to instinct, the only peculiarity of such a reaction would be
that the sense-impression calling forth the act would be the
same act as done by another. [If due to experience, there
would be an exact correspondence to the frequent acts
called forth originally by several elements in a sense-im-
pression, one of which is essential, and done afterwards
when only the non-essentials are present. These two
possibilities have not been sufficiently realized, yet they
may contain the truth. On the other hand, these limited
acts may be the primitive, sporadic beginnings of the
general imitative faculty which we find in man. To this
general faculty we may now turn, having cleared away
some of the more doubtful phenomena which have shared
its name.

It should be kept in mind that an imitative act may be
performed quite unthinkingly, as when a man in the mob
shouts what the others shout or claps when the others clap;
may be done from an inference that since A by doing X makes
pleasure for himself, I by doing X may get pleasure for my-
self; may, lastly, be done from what may be called a trans-
ferred association. This process is the one of interest in
connection with our general topic, and most of my ex-
periments on imitation were directed to the investigation
of it. Its nature is simple. One sees the following se-
quence: ‘A turning a faucet, A getting a drink.’ If one
can free this association from its narrow confinement to A,
so as to get from it the association, ‘impulse to turn faucet,
me getting a drink,’ one will surely, if thirsty, turn the
faucet, though he had never done so before. If one can
from an act witnessed learn to do the act, he in some way

80 Animal Intelligence

makes use of the sequence seen, transfers the process to
himself; in the common human sense of the word, he
imitates. This kind of imitation is surely common in
human life. It may be apparent in ontogeny before any
power of inference is shown. After that power does appear,
it still retains a wide scope, and teaches us a majority, per-
haps, of the ordinary accomplishments of our practical life.

Now, as the writers of books about animal intelligence
have not differentiated this meaning from the other possible
ones, it is impossible to say surely that they have uniformly
credited it to animals, and it is profitless to catalogue here
their vague statements. Many opposers of the ‘reason’
theory have presupposed such a process and used it to replace
reason as the cause of some intelligent performances. The
upholders of the reason theory have customarily recognized
such a process and claimed to have discounted it in their
explanations of the various anecdotes. So we found
Mr. Romanes, in the passage quoted, discussing the possi-
bility that such an imitative process, without reason, could
account for the facts. In his chapter on Imitation in
‘Habit and Instinct,’ Principal C. Lloyd Morgan, the sanest
writer on comparative psychology, seems to accept imita-
tion of this sort as a fact, though he could, if attacked,
explain most of his illustrations by the simple forms. The
fact is, as was said before, that no one has analyzed or
systematized the phenomena, and so one cannot find clear,
decisive statements to quote.

At any rate, whether previous authorities have agreed
that such a process is present or not, it is worth while to
tackle the question; and the formation of associations by
imitation, if it occurs, is an important division of the forma-
tion of associations in general. The experiments and their
results may now be described.

Experimental Study of Associative Processes 81

IMITATION IN CHICKS

No. 64 learned to get out of a certain pen (16 X 10 inches)
by crawling under the wire screening at a certain spot.
There was also a chance to get out by walking up an inclined
plane and then jumping down. No. 66 was put in with 64.
After g minutes 20 seconds, 66 went out by the inclined
plane, although 64 had in the meantime crawled out under
the screen g times. (As soon as he got out and ate a little

Fic. 19. FIG. 20.

he was put back.) It was impossible to judge how many
of these times 66 really saw 64 do this. He was looking in
that direction 5 of the times. So also, in three more trials,
66 used the inclined plane, though 64 crawled under each
time. 67 was then tried. In 4 minutes ro seconds, he
crawled under, 64 having done so twice. Being then put
in alone, he, without the chance to imitate, still crawled
under. So probably he went under when with 64 not by
imitation but by accident, just as 64 had learned the thing
himself.

The accompanying figure (19) shows the apparatus used
in the next experiment. A represents the top of a box
(5 X 4 inches), 13 inches above the level of the floor C.
On the floor C were the chicks and food. B is the top of
a box 10 inches high. Around the edges of A except the

one next B a wire screen was placed, and 65 was repeatedly
G

82 Animal Intelligence

put upon A until he learned to go quickly back to C wa B.
Then the screen was bent outward at X so that a chick
could barely squeeze through and down (A to C). Eleven
chicks were then one at a time placed on A with 65. In
every case but one they went A-C. In the case of the chick
(75) who went A—-B-C, there could have been no imitation,
for he went down before 65 did. One other went through
the hole before 65 went to B. The remaining nine all had
a chance to imitate 65 and to save the uncomfortable
struggle to get through the hole, 65 going A-B-C 8 times
before 68 went A-C, 2 times when with 66 and 76, once in
the case of each of the others.

In still another experiment the apparatus was (as shown in
Fig. 20) a pen 14 inches square, 10 inches high, with a wire
screen in front and a hole 33 inches square in the back.
This hole opened into a passageway (B) leading around to C,
where were the other chicks and food. Chicks who had
failed, when put in alone, to find the way out, were put in
with other chicks who had learned the way, to see if by
seeing them go out they would learn the way. Chick 70
was given 4 trials alone, being left in the box 76 minutes all
told. He was then given g trials (165 minutes) with another
chick who went out via B 36 times. 7o failed to follow him
on any occasion. The trials were all given in the course
of two days. Chick 73 failed in 1 trial (12 minutes) to get
out of himself, and was then given 4 trials (94 minutes)
with another chick who went out via B 33 times. In this
experiment, as in all others reported, sure evidence that the
animals wanted to get out, was afforded by their persistent
peckings and jumpings at the screen or bars that stood
between them and C. Chick 72, after 8 unsuccessful trials
alone (41 minutes), was given 8 trials with a chance to
imitate. After the other chick had gone out 44 times, 72

Experimental Study of Associative Processes 83

did go out. Hedid not follow the other but went 20 seconds
later. It depends upon one’s general opinion whether one
shall attribute this one case out of three to accident or
imitation.

I also took two chicks, one of whom learned to escape
from A (in Fig. 19) by going to B and jumping down the
side to the right of A, the other of whom learned to jump
down the side to the /eft, and placed them together upon A.
Each took his own course uninfluenced by the other in 10 trials.

Chicks were also tried in several pens where there was only
one possible way of escape to see if they would learn it more
quickly when another chick did the thing several times before
their eyes. The method was to give some chicks their first
trial with an imitation possibility and their second without,
while others were given their first trial without and their
second with. If the ratio of the average time of the first
trial to the average time of the second is smaller in the first
class than it is in the second class, we may find evidence of
this sort of influence by imitation. Though imitation may
not be able to make an animal do what he would otherwise
not do, it may make him do quicker a thing he would have
done sooner or later any way. As a fact the ratio is much
larger. ‘This is due to the fact that a chick, when in a pen
with another chick, is not afflicted by the discomfort of lone-
liness, and so does not try so hard to get out. So the other
chick, who is continually being put in with him to teach
him the way out, really prolongs his stay in. This factor
destroys the value of these quantitative experiments, and
I do not insist upon them as evidence against imitation,
though they certainly offer none for it. I do not give
descriptions of the apparatus used in these experiments or a
detailed enumeration of the results, because in this dis-
cussion we are not dealing primarily with imitation as a

84 Animal Intelligence

slight general factor in forming experience, but as a definite
associational process in the mind. The utter absence of
imitation in this limited sense is apparently demonstrated
by the results of the following experiments.

V was a box 16 X 12 X 83, with the front made of wire
screening and at the left end a little door held by a bolt but
in such a way that a sharp peck at the top of the door would
force it open.

W was a box of similar size, with a door in the same place
fixed so that it was opened by raising a bolt. To this bolt
was tied a string which went up over the top of the edge of
the box and back across the box, asin D. By jumping up
and coming down with the head over this thread, the bolt
wouldbepulledup. The thread was 8% inches above the floor.

X was a box of similar size, with door, bolt and string
likewise. But here the string continued round a pulley at
the back down to a platform in the corner of the box. By
stepping on the platform the door was opened.

Y was a box 12 X 8 X 83, witha door in the middle of the
front, which I myself opened when a chick pecked at a tack
which hung against the front of the box 13 inches above the
top of the door.

These different acts, pecking at a door, jumping up and
with the neck pulling down a string, stepping on a platform,
and pecking at a tack, were the ones which various chicks
were given a chance to imitate. The chicks used were from
16 to 30 days old. The method of experiment was to put
a chick in, leave him 60 to 80 seconds, then put in another
who knew the act, and on his performing it, to let both
escape. No cases were counted unless the imitator ap-
parently saw the other do the thing. After about ten such
chances to learn the act, the imitator was left in alone for
ten minutes. The following table gives the results. The

Experimental Study of Associative Processes 85

imitators, of course, had previously failed to form the asso-
ciation of themselves. F denotes failure to perform the act:

TABLE 4

CHICK Act No. Tres SAW Sida ee FINAL Time
84 Vv 38 45.00 F 15.00 F
85 Vv 30 30.00 F 10.00 F
86 V 44 55.00 F 15.00 F
87 V 26 35.00 F 15.00 F
80 W 54 60.00 F 15.00 F
81 W 40 45.00 F 15.00 F
87 W 27 30.00 F 10.00 F
81 x 18 20.00 F 10.00 F
82 xX 21 20.00 F 8.40 Did
83 xX 33 35.00 F 15.00 F
84 xX 46 55.00 F 15.00 F
84 Y 45 55.00 F 15.00 F
83 x 29 35.00 F 15.00 F

Thus out of all these cases only one did the act in spite of
the ample chance for imitation. I have no hesitation in
declaring 82’s act in stepping on the platform the result
of mere accident, and am sure that any one who had watched
the experiments would agree.

IMITATION IN CATS

By reference to the previous descriptions of apparatus, it
will be seen that box D was arranged with two compart-
ments, separated by a wire screen. ‘The larger of these had
a front of wooden bars with a door which fell open when a
string stretched across the top was bitten or clawed down.
The smaller was closed by boards on three sides and by the
wire screen on the fourth. Through the screen a cat within
could see the one to be imitated pull the string, go out

86 Animal Intelligence

through the door thus opened and eat the fish outside.
When put in this compartment, the top being covered by
a large box, a cat soon gave up efforts to claw through the
screen, quieted down and watched more or less the proceed-
ings going onin the other compartment. ‘Thus this appara-
tus could be used to test the power of imitation. A cat who
had no experience with the means of escape from the large
compartment was put in the closed one; another cat, who
would do it readily, was allowed to go through the per-
formance of pulling the string, going out, and eating the
fish. Record was made of the number of times he did so
and of the number of times the imitator had his eyes clearly
fixed on him. These were called ‘times seen.’ Cases
where the imitator was looking in the general direction
of the ‘imitatee’ and might very well have seen him and
probably did, were marked ‘doubtful.’ In the remaining
cases the cat did not see what was done by his instructor.
After the imitatee had done the thing a number of times,
the other was put in the big compartment alone, and the
time it took him before pulling the string was noted and
his general behavior closely observed. If he failed in 5 or 10
or 15 minutes to do so, he was released and not fed. This
entire experiment was repeated a number of times. From
the times taken by the imitator to escape and from obser-
vation of the way that he did it, we can decide whether imi-
tation played any part. The history of several cases are
given in the following tables. In the first column are given
the lengths of time that the imitator was shut up in the box
watching the imitatee. In the second column is the number
of times that the latter did the trick. In the third and
fourth are the times that the imitator surely and possibly
saw it done, while in the last is given the time that, when
tried alone, the imitator took to pull the string, or if

Experimental Study of Associative Processes 87

he failed, the time he was in the box trying to get out.
Times are in minutes and seconds, failures denoted by F :
TABLE 5 (a)

No. 7 Immratinc No. 2

Time No. of times | No. of times | No. of times] Time of 7

Watching 2 did 7 saw Doubtful | when alone
1000. II 3 5
After 48 Hours 11.00 10 4 2
12.00 20 4 13 10.00 F
1.00}
After 24 Hours 8.00 20 6 II 3.30
10.00 F
13.00 25 8 4 a7) 20.00 F
After 24 Hours 9.00 20 4 II 10.00 F
After 24 Hours 12.00 35 5 21 30.00 F
After 2 Hours 10.00 25 3 8 25.00 F
After 24 Hours 15.00 35 6 21 20.00 F
After 24 Hours 6.00 20 ° 7 10.00 F
Total times surely and possibly seen, - 43 III
TABLE 5 (b)

No. 5 ImitTaTinc No. 2 |

Time No. of times|No. of times|No. of times} Time of 5
Watching 2 did 5 saw Doubtful | when alone
12.00 15 3 8 5.00 F
After 2 Hours 10.00 8 4 4
After 24 Hours 5-00 5 ° 2
After 1 Hour 14.00 se) 5 3 10.00 F
After 1 Hour 13.00 22 7 II 10.00 F
After 24 Hours 7.00 15 3 8 5.00 F
After 48 Hours 18.00 20 2 9 20.00 F
After 24 Hours 14.00 20 2 IO 30.00 F
After 24 Hours 10.00 20 7 12 20.00 F
Total times surely and possibly seen, - 33 68

1 No. 7 hit the string in his general struggling, apparently utterly without
design. He did not realize that the door was open till, two seconds after it
had fallen, he happened to look that way.

88 Animal Intelligence
TABLE 5 (c)

No. 6 Imitatinc No. 2

Time No. of times/No. of times) No. of times} Time of 6

Watching 2 did 6 saw Doubtful | when alone
12.00 30 fo) 19 r:101
After 48 Hours 11.00 30 ° vit 9.30
After 72 Hours 10.00 30 ° 15 3.00
After 72 Hours 6.00 20 q 7 1.50
After 24 Hours 9.00 30 a 13 10.00 F
After 24 Hours 10.00 30 6 9 10.00 F
After 24 Hours 10.00 30 I 8 9.40
Total times surely and possibly seen, - 11 82
TABLE 5 (d)
No. 3 Iurratinc No. 2
8.00 30 2 19 3.907
3-39
After 48 Hours 10.00 30 2 14 .20
.20
After 72 Hours 10.00 30 2 8 18
.08
Total times surely and possibly seen, - 6 AI

Before entering upon a discussion of the facts shown by
these tables, we must describe the behavior of the imitators,
when, after seeing 2 pull the string, they were put in alone.
In the opinion of the present observer there was not the

1 No. 6, in trying to crawl out at the top of the box, put its paw in above
the string. It fell down and thus pulled the string. It did not claw at it,
and it was 16 seconds before it noticed that the door was open. In all
the other times that it escaped the movement was made in the course of
promiscuous scrambling, never in anything like the same way that No. 2
made it.

2 No. 3 did not go out until 12 seconds had elapsed after it had pulled the
string.

Experimental Siudy of Associative Processes 8g

slightest difference between their behavior and that of cats
4, 10, II, 12 and 13, who were put into the same position
without ever having seen 2 escape from it. 6, 7, 5 and 3
paid no more attention to the string than they did, but
struggled in just the same way. Noone, Iam sure, who had
seen them, would have claimed that their conduct was at all
influenced by what they had seen. When they did hit the
string the act looked just like the accidental success of the
ordinary association experiment. But, besides these per-
sonal observations, we have in the impersonal time-records
sufficient proofs of the absence of imitation. If the ani-
mals pulled the string from having seen 2 do so, they ought
to pull it in each individual case at an approximately regular
length of time after they were put in, and presumably pretty
soon thereafter. That is, if an association between the sight
of that string in that total situation and a certain impulse
and consequent freedom and food had been formed in their
minds by the observation of the acts of 2, they ought to pull
it on seeing it, and if any disturbing factor required that a
certain time should elapse before the imitative faculty got
in working order, that time ought to be somewhere near
constant. The times were, as a fact, long and irregular in
the extreme. Furthermore, if the successful cases were
even in part due to imitation, the times ought to decrease
the more they saw 2 do the thing. Except with 3, they zn-
crease or give place to failures. Whereas 6 and 7, if they
had been put in again immediately after their first success-
ful trial and from then on repeatedly, would have unques-
tionably formed the association, they did not, when put in
after a further chance to increase their knowledge by imita-
tion, do the thing as soon as before. The case of 3 is not
here comparable to the rest because he was given three trials
in immediate succession. He was a more active cat and

go Animal Intelligence

quicker to learn, as may be seen by comparing his time
curves with those of 7,6 and 5. That the mere speed with
which he mastered this association is no sign that imitation
was present may be seen by reference to the time curves of
4 and 13 (on p. 43).

Some cats were also experimented with in the following
manner. They were put into a box [No. 7 into box A (O at
front), No. 5 into B (O at back)|and left for from 45 to 75 sec-
onds. Then a cat who knew the way to get out was put in,
and, of course, pulled at the loop and opened the door. Both
cats then went out and both were fed. After the cat had been
given a number of such chances to learn by imitation, he
was put in and left until he did the thing, or until 5 or 10
minutes elapsed. As in the preceding experiments, no
change in their behavior which might signify imitation was
observed. No. 7 acted exactly like 3, or 10, or 11, when put
in the box, apparently forming the association by accident
in just the same way. Good evidence that he did not imi-
tate is the fact that, whereas 1 (whom he saw) pulled the
loop with his teeth, 7 pulled it with his paw. ‘5 failed to form
the association, though he saw 3 do it 8 times and probably
saw him 18 times more. He did get out twice by clawing
the string in the front of the box, not the Joop in the back,
as 3 did. These successes took place early in the experi-
ment. After that he failed when left alone to get out at
all.

Another experiment was made by a still different method.
My cats were kept in a large box about 4 ft. high, the front
of which was covered with poultry-yard netting. Its top
was a board which could be removed. To save opening the
door and letting them all loose, I was in the habit of taking
them out by the top when I wanted to experiment with
them. Of course the one who happened to climb up (per-

Experimental Study of Associative Processes 91

haps attracted by the smell of fish on my fingers) was most
likely to be taken out and experimented with andfed. Thus
they formed the habit of climbing up the front of the box
whenever I approached. Of three cats which I obtained at
the same time, one did not after 8 or 1o days acquire this
habit. Even though I held out a piece of fish through the
netting, he would not climb after it. It was reasonable to
suppose that imitation might overcome this sluggishness,
if there were any imitation. I therefore put two cats with
him and had them climb up 80 times before his eyes and get
fish. He never followed or tried to follow them.

4 and 3 had been subjected to the following experiment.
I would make a certain sound and after 10 seconds would go
up to the cage and hold the fish out to them through the
netting at the top. They would then, of course, climb up
and eat it. After a while, they began to climb up upon
hearing the signal (4) or before the 10 seconds were up. I
then took 12 and 10, who were accustomed to going up when
they saw me approach, but who had no knowledge of the
fact that the signal meant anything, and gave them each a
chance to imitate 3. That is, one of them would be left in
the box with 3, the signal would be given, and after from 5
to ro seconds 3 would climb up. At 1o seconds I would
come up with food, and then, of course, 12 would climb up.
This was repeated, again and again. The question was
whether imitation would lead them to form the association
more quickly than they would have done alone. It did not.
That when at last they did climb up before 10 seconds
was past, that is, before I approached with food, it was not
due to imitation, is shown by the fact that on about half
of such occasions they climbed up before 3 did. That is,
they reacted to the signal by association, not to his move-
ments by imitation.

g2 Animal Intelligence

IMITATION IN Docs

Here the method was not to see if imitation could arouse
more quickly an act which accident was fairly likely to bring
forth sooner or later, but to see if, where accident failed,
imitation would succeed.

3 was found to be unable of himself to escape from box
BB1, and was then given a chance to learn from watching 1.
The back of box BBr was torn off and wire netting substi-
tuted for it. Another box with open front was placed di-
rectly behind and against box BB1. No. 3, who was put in
this second box, could thus see whatever took place in and
in front of box BB1 (Oat back, high). The record follows :—

TABLE 6 (a)

Doc 3 Imitatinc Doc 1

Times Times Times prob- Time
I did 3 saw ably 3 saw in alone
30 7 14 3.00) F
After 1 Hour 35 9 14 3.00 EF
After 1 Hour 10 a 3 5.00 F
After 24 Hours 20 6 8
30 8 13 6.00 F
After 48 Hours 25 8 II 8.00 F
25 6 12 6.00 F
25 9 7 10.00 F
After 24 Hours 30 IO II 40.00 F
Total times surely and possibly seen, - 66 93

A similar failure to imitate was observed in the case of
another simple act. No. 1, as may be seen on page 60,
had learned to escape from a pen about 8 by 5 feet by jump-
ing up and biting a cord which ran from one end of the pen to
the other and at the front end was tied to the bolt which
held the door. Dogs 2 and 3 had failed in their accidental

Experimental Study of Associative Processes 93

jumping and pawing to hit this cord, and were then given a
chance to learn by seeing 1 do so, escape, and, of course, he
fed. 1 always jumped in the same way, biting the cord at
the same place, namely, where a loose end from a knot in it
hung down 4 or 5 inches. 2 and 3 would either be tied up
in the pen or left in a pen at one side. They had a perfect
chance to see 1 perform his successful act. After every
twenty or thirty performances by 1, 2 and 3 would be put in
alone. It should be remembered that here, as also in the
previous experiment and all others, the imitators certainly
wanted to get out when thus left in alone. They struggled
and jumped and pawed and bit, but they never jumped af
the cord. ‘Their records follow: —

TABLE 6 (b)

Doc 2 Inmitatinc Doc 1

Times Times Times Time 2 was
1 did 2 saw Doubtful in alone
30 9 II 10.00 F
After 1 Hour 30 if) 9 10.00 F
After 48 Hours 25 8 8
After 1 Hour ite) 3 4 g.oo F!
After 24 Hours 30 8 12 15.00 F
After 1 Hour 30 9 12 15.00 F
After 48 Hours 20 7 6 10.00 F
20 Sat 7
After 48 Hours 30 6 8 15.00 F
After 24 Hours 15 2 4 10.00 F
Total times surely and possibly seen, - 70 81

1 The back of the pen adjoined the elevator shaft, being separated from it
by a partition 33 inches high. No. 2 heard the elevator coming up and put
his paws up on the top of this partition so as to look over. In so doing he
knocked the fastening of the cord at that end and opened the door. He
did not turn to come out, and I shut the door again.

94 Animal Intelligence

TABLE 6 (c)

Doc 3 ImrratTinc Doc 1

Times Times Times Time 3 was
1 did 3 saw Doubtiul in alone

30 be) se) 10.00 F

After 1 Hour 30 9 10 10.00 F
After 1 Hour 15 6 4

After 24 Hours 30 9 II 15.00 F

After 24 Hours 30 se) 12 15.00 F

After 1 Hour 30 8 9 10.00 F

After 48 Hours 20 6 7 40.00 F
After 1 Hour 20 6 5

After 48 Hours 30 8 9 15.00 F

After 24 Hours 15 3 4 20.00 F
Total times surely and possibly seen, - 75 81

Another corroborative, though not very valuable, experi-
ment was the following: Dog 3 had been taught for the pur-
pose of another experiment to jump up on a box and beg
when I held a piece of meat above the box. I then caused
him to do this rro times (within two days) in the presence of
1. Although 1 saw him at least 20 per cent of the times (3
was always fed each time he jumped on the box), he never
tried to imitate him.

It seems sure from these experiments that the animals
were unable to form an association leading to an act from
having seen the other animal, or animals, perform the act in
a certain situation. Thus we have further restricted the
association process. Not only do animals not have asso-
ciations accompanied, more or less permeated and altered,
by inference and judgment; they do not have associations
of the sort which may be acquired from other animals by
imitation. What this implies concerning the actual mental

Experimental Study of Associative Processes 95

content accompanying their acts will be seen later on. It
also seems sure that we should give up imitation as an a
priort explanation of any novel intelligent performance.
To say that a dog who opens a gate, for instance, need not
have reasoned it out zf he had seen another dog do the same
thing, is to offer, instead of one false explanation, another
equally false. Imitation in any form is too doubtful a
factor to be presupposed without evidence. And if a
general imitative faculty is not sufficiently developed to
succeed with such simple acts as those of the experiments
quoted, it must be confessed that the faculty is in these
higher mammals still rudimentary and capable of influ-
encing to only the most simple and habitual acts, or else
that for some reason its sphere of influence is limited to
a certain class of acts, possessed of some qualitative difference
other than mere simplicity, which renders them imitable.
The latter view seems a hard one to reconcile with a sound
psychology of imitation or association at present, without
resorting to instinct. Unless a certain class of acts are by
the innate mental make-up especially tender to the in-
fluence of imitation, the theory fails to find good psychologi-
cal ground to stand on. The former view may very well be
true. But in any case the burden of proof would now seem
to rest upon the adherents to imitation; the promising
attitude would seem to be one which went without imitation
as long as it could, and that is, of course, until it surely found
it present.

Returning to imitation considered in its human aspect, to
imitation as a transferred association in particular, we find
that here our analytical study of the animal mind promises
important contributions to general comparative psychology.
If it is true, and there has been no disagreement about it,
that the primates do imitate acts of such novelty and com-

96 Animal Intelligence

plexity that only this out-and-out kind of imitation can ex-
plain the fact, we have located one great advance in mental
development. ‘Till the primates we get practically nothing
but instincts and individual acquirement through impul-
sive trial and error. Among the primates we get also ac-
quisition by imitation, one form of the increase of mental
equipment by tradition. The child may learn from the
parent quickly without the tiresome process of seeing for
himself. The less active and less curious may share the
progress of their superiors. The brain whose impulses
hitherto could only be dislodged by specific sense-impres-
sions may now have any impulse set agoing by the sight of
the movement to which it corresponds.

All this on the common supposition that the primates do
imitate, that a monkey in the place of these cats and dogs
would have pulled the string. My apology for leaving the
matter in this way without experiments of my own is that
the monkey which I procured for just this purpose failed in
two months to become tame enough to be thus experimented
on. Accurate information about the nature and extent of
imitation among the primates should be the first aim of
further work in comparative psychology, and will be sought
by the present writer as soon as he can get subjects fit for
experiments.

Ina questionnaire which was sent to fifteen animal trainers,
the following questions were asked : —

1. “If one dog was in the habit of ‘begging ’ to get food and
another dog saw him do it ten or twenty times, would the second
dog then beg himself ?”’

2. “In general is it easier for you to teach a cat or dog a trick
if he has seen another do it ?”

3. “In general do cats imitate each other? Do dogs? Do
monkeys? ”

Experimental Study of Associative Processes 97

4. “Give reasons for your opinion, and please write all the
reasons you have.”

Five gentlemen (Messrs. R. C. Carlisle, C. L. Edwards, V. P.
Wormwood, H. S. Maguire and W. E. Burke) courteously re-
sponded to my questionnaire. All are trainers of acknowledged
reputation. To these questions on imitation four replied.

To the first question we find the following answers: (a)
“Most dogs would.” (0) “Yes; he will very likely doit. He
will try and imitate the other dog generally.” (c) “If a young
dog with the mother, it would be very apt to.... With
older dogs, it would depend very much upon circumstances.”
(d) ‘‘He would not.”

To 2 the answers were: (a) ‘Very much easier.” (0) “It
is always easier if they see another one do it often.” (c) “This
would also depend on certain conditions. In teaching to jump
out of a box and in again, seeing another might help, but in
teaching something very difficult, I do not think it would be the
ease?) 5 (2): tas not,”

To 3 the answers were: (a) “Yes. Some. More than
either dogs or cats.” (b) “Yes. Yes. Yes.” (c) “In certain
things, yes; mostly in those things which are in compliance to
the laws of their own nature.” (d) ‘‘No. No. Yes, they are
born imitators.”

The only definite answer to question 4 was: “Take a dog or
cat and close them up in a room and go in and out several times,
and you will find that they will go to the door and stand up on
their hind legs with front paws on the door knob and try to open
the door to get out. I could also give you a hundred more such
reasons.” This was given by (0).

The replies to a test question, however, go to show that
these opinions regarding imitation may be mistaken. Ques-
tion 8 was: ‘“‘If you wanted to teach a cat to get out of a °
cage by opening an ordinary thumb latch and then pushing
the door, would you take the cat’s paw and push down the

thumb piece with it and then push the door open with the
H

98 Animal Intelligence

paw, or would you just leave the cat inside until it learned
the trick itself ?’? ‘The second is certainly the better way,
as will be seen in a later part of this paper, and pushing the
latch with the cat’s paw has absolutely no beneficial in-
fluence on the formation of the association, yet (a) and (6)
both chose the first way, and (c) answered ambiguously.
Further, the only reason given is, of course, no reason at all.
It proves too much, for if there were such imitation as that,
my cats and dogs would surely have done the far simpler
things required of them. I cannot find that trainers
make any practical use of imitation in teaching animals
tricks, and on the whole I think these replies leave the mat-
ter just where it was before. They are mere opinions —
not records of observed facts. It seems arrogant and may
seem to some unjustifiable thus to discard testimony, to
stick to a theory based on one’s own experiments in the face
of these opinions. If I had wished to gain applause and
avoid adverse criticism, I would have abstained from up-
holding the radical view of the preceding pages. At times
it seems incredible to me that the results of my experi-
ments should embody the truth of the matter, that there
should be no imitation. The theory based on them seems,
even to me, too radical, too novel. It seems highly improb-
able that I should be right and all the others wrong. But I
cannot avoid the responsibility of giving what seems to my
judgment the most probable explanation of the results of
the experiments; and that is the radical explanation al-
ready given.

THE MENTAL FAct IN ASSOCIATION

It is now time to put the question as to just what is in an
animal’s mind when, having profited by numerous experi-

Experimental Study of Associative Processes 99

ences, he has formed the association and does the proper act
when put in a certain box. The commonly accepted view
of the mental fact then present is that the sight of the inside
of the box reminds the animal of his previous pleasant ex peri-
ence after escape and of the movements which he made which
were immediately followed by and so associated with that
escape. It has been taken for granted that if the animal
remembered the pleasant experience and remembered the move-
ment, he would make the movement. It has been assumed
that the association was an association of ideas; that when
one of the ideas was of a movement the animal was capable
of making the movement. So, for example, Morgan says, in
the ‘Introduction to Comparative Psychology’ : “If a chick
takes a ladybird in its beak forty times and each time finds
it nasty, this is of no practical value to the bird unless the
sight of the insect suggests the nasty taste”’ (p. go).

Again, on page 92, Morgan says, ‘“‘A race after the ball had
been suggested through the channel of olfactory sensations.”’
Also, on page 86 “‘. . . the visual impression suggested
the idea or representation of unpleasant gustatory experi-
ence.” The attitude is brought out more completely in a
longer passage on page 118: “On one of our first ascents
one of them put up a young coney, and they both gave chase.
Subsequently they always hurried on to this spot, and,
though they never saw another coney there, reiterated dis-
appointment did not efface the memory of that first chase, or
so it seemed.” That is, according to Morgan, the dogs
thought of the chase and its pleasure, on nearing the spot
where it had occurred, and so hurried on. On page 148 of
‘ Habit and Instinct,’ we read, ‘‘Ducklings so thoroughly
associated water with the sight of their tin that they tried
to drink from it and wash in it when it was empty, nor did
they desist for some minutes,” and this with other similar

100 Animal Intelligence

phenomena is attributed to the ‘association by contiguity’
of human psychology.

From these quotations it seems fairly sure that if we
should ask Mr. Morgan, who is our best comparative psy-
chologist, what took place in the mind of one of these cats
of our experiments during the performance of one of the
‘ tricks ’ he would reply: ‘‘The cat performs the act because
of the association of ideas. He is reminded by the sight of
the box and loop of his experience of pulling that loop and of
eating fish outside. So he goes and pulls it again.” This
view has stood unchallenged, but its implication is false. It
implies that an animal, whenever it thinks of an act, can
supply an impulse to do the act. It takes for granted
that the performance of a cat who gets out of a box is men-
tally like that of a man who thinks of going down street
or of writing a letter and then does it. The mental process
is not alike in the two cases, for animals can not provide the
impulse to do whatever act they think of. No cat can form
an association leading to an act unless there 1s included in the
association an impulse of its own which leads to the act. ‘There
is no general storehouse from which the impulse may be sup-
plied after the association is formed.

Before describing the experiments which justify these
statements, it will be worth while to recall the somewhat ob-
vious facts about the composition of one of these associa-
tions. ‘There might be in an association, such as is formed
after experience with one of our boxes, the following ele-
Mens .-—

I. Sense-impression of the interior of the box, etc.

(a) Discomfort and (6) desire to get out.
Representation of oneself pulling the loop.
Fiat comparable to the human “‘T’ll do it.”
The impulse which actually does it.

mm BW bd

Experimental Study of Associative Processes 101

6. Sense-impression of oneself pulling the loop, seeing
one’s paw in a certain place, feeling one’s body in a certain
way, etc.

7. Sense-impression of going outside.

8. Sense-impression of eating, and the included pleasure.

Also between 1 and 4 we may have 9, representations of
one’s experience in going out, 10, of the taste of the food, etc.
6, 7 and 8 come after the act and do not influence it, of
course, except in so far as they are the basis of the future
3's, 9’s and 10’s. About 2 we are not at present disputing.
Our question is as to whether 3 or 5 is the essential thing.
In human associations 3 certainly often is, and the animals
have been credited with the same kind. Whatever he thinks,
Professor Morgan surely talks as if 1 aroused g and 10 and 3
and leaves 5 to be supplied at will. We have affirmed that
5 is the essential thing, that no association without a specific
5 belonging to it and acquired by it can lead toan act. Let
us look at the reasons.

A cat has been made to go into a box through the door,
which is then closed. She pulls a loop and comes out and
gets fish. She is made to go in by the door again, and again
lets herself out. After this has happened enough times, the
cat will of her own accord go into the box after eating the
fish. It will be hard to keep her out. The old explanation
of this would be that the cat associated the memory of being
in the box with the subsequent pleasure, and therefore per-
formed the equivalent of saying to herself, ‘Go to! I will
goin.” The thought of being in, they say, makes her go in.
The thought of being in will not make her go in. For if, in-
stead of pushing the cat toward the doorway or holding it
there, and thus allowing it to itself give the impulse, to in-
nervate the muscles, to walk in, you shut the door first and
drop the cat in through a hole in the top of the box, she will,

102 Animal Intelligence

after escaping as many times as in the previous case, not go
into the box of her own accord. She has had exactly the
same opportunity of connecting the idea of being in the box
with the subsequent pleasure. Either a cat cannot connect
ideas, representations, at all, or she has not the power of
progressing from the thought of being in to the act of going
in. The only difference between the first cat and the sec-
ond cat is that the first cat, in the course of the experience,
has the impulse to crawl through that door, while the second
has not the impulse to crawl through the door or to drop
through that hole. So, though you put the second cat on
the box beside the hole, she doesn’t try to get into the box
through it. The impulse is the szne qua non of the associa-
tion. The second cat has everything else, but cannot sup-
ply that. ‘These phenomena were observed in six cats, three
of which were tried by the first method, three by the
second. Of the first three, one went in himself on the 26th
time and frequently thereafter, one on the 18th and the other
on the 37th; the two last as well as the first did that fre-
quently in later trials. The other three all failed to go in
themselves after 50, 60 and 75 trials, respectively.

The case of No. 7 was especially instructive, though not
among these six. No. 7 had had some trials in which it was
put in through the door, but ordinarily in this particular
experiment was dropped in. After about 80 trials it would
frequently exhibit the following phenomena: It would,
after eating the fish, go up to the doorway and, rushing
from it, search for fish. The kitten was very small and
would go up into the doorway, whirl round and dash out,
all in one quick movement. The best description of its
behavior is the paradoxical one that it went out without
going in. The association evidently concerned what it had
done, what it had an impulse for, namely, coming out through

Experimental Study of Associative Processes 103

that door to get fish, not what it remembered, had a repre-
sentation of.

Still more noteworthy evidence is found in the behavior of
cats and dogs who were put in these boxes, left one or two
minutes, and then put through the proper movement.
For example, a cat would be put in B (O at back) and left
two minutes. I would then put my hand in through the
top of the box, take the cat’s paw and with it pull down the
loop. The cat would then go out and eat the fish. This
would be done over and over again, and after every ten
or fifteen such trials the cat would be left in alone. If in
ten or twenty minutes he did not escape, he would be taken
out through the top and not fed. In one series of experi-
ments animals were taken and thus treated in boxes from
which their own impulsive activity had failed to liberate
them. The results, given in the table below, show that no
animal who fails to perform an act in the course of his own
impulsive activity will learn it by being put through it.

In these experiments some of the cats and all of the dogs
but No. 1 showed no agitation or displeasure at my handling
from the very start. Nor was there any in Dog 1 or the other
cats after a few trials. It may also be remarked that in
the trials alone which took place during and at the end of
the experiment the animals without exception showed that
they did not fail to perform the act from lack of a desire to
get out. They all tried hard enough to get out and would
surely have used the association if they had formed it.

Now, the only difference between the experiences of the
animals in these experiments and their experiences in those
where they let themselves out, is that here they only saw
and felt themselves making the movement, whereas in the
other case they also felt the impulse, gave the innervation.
That, then, is the essential. It may be objected that the

104 Animal Intelligence

prom EMail
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animals failed because they did not attend to the process
of being put through the movement, that, had they attended
to it, they would later themselves have made the movement.
It is, however, improbable that out of fifty times an animal
should not have attended to what was going on at least two
or three times. But if seeing himself do it was on a par with
feeling an impulse to and so doing it, even two or three
times would suffice to start the habit. And it is even more
improbable that an experience should be followed by keen
pleasure fifty times and not be attended to with might and

1 FF was a box 40 X 21 X 24 inches, the door of which could be opened
by putting the paw out between the bars to its right and pulling a loop which
hung 16 inches above the floor, 4 inches out from the box and 6 inches to
the right of the door.

* KKK was box K with both bolts removed. All that had to be done
was to poke the paw out at one side of the door and press down a little bar of
wood.

3 The cats and chick were left in for two minutes at each trial, the dogs
for from one to one and a half minutes.

Experimental Study of Associative Processes 105

main, unless animals attend only to their own impulses and
the excitements thereof. But if the latter be true, it simply
affrms our view from a more fundamental standpoint.

In another set of experiments animals were put in boxes
with whose mechanisms they had had no experience, and
from which they might or might not be able to escape by
their own impulsive acts. The object was to see whether
the time taken to form the association could be altered by
my instruction. The results turned out to give a better
proof of the inability to form an association by being put
through the act than any failure to change the time-curve.
For it happened in all but one of the cases that the move-
ment which the animal made to open the door was different
from the movement which I had put him through. Thus,
several cats were put through (in Box C [button]) the follow-
ing movement: I took the right paw and, putting it against
the lower right-hand side of the button, pushed it round
to a horizontal position. The cats’ ways were as follows:
No. 1 turned it by clawing vigorously at its top; No. 6,
by pushing it round with his nose; No. 7, in the course of
an indiscriminate scramble at first, in later trials either by
pushing with his nose or clawing at the top, settling down
finally to the last method. Nos. 2 and 5 did it as No. 1 did.
Cat 2 was tried in B (O at back). I took his paw and pressed
the loop with it, but he formed the habit of clawing and
biting the string at the top of the box near the front. No.1
was tried in A. I pressed the loop with his paw, but he
formed the habit of biting at it.

In every case I kept on putting the animal through the act
every time, if at the end of two minutes (one in several
cases) it had not done it, even after it had shown, by using
a different way, that my instruction had no influence. I
never succeeded in getting the animal to change its way for

106 Animal Intelligence

mine. Moreover, if any one should fancy that the animal
really profited by my instruction so as to learn what result
to attain, namely, the turning of a certain button, but
chose a way of his own to turn it, he would be deluding
himself. The time taken to learn the act with instruction
was no shorter than without.

If, then, an animal happens to learn an act by being put
through it, it is just happening, nothing more. Of course,
you may direct the animal’s efforts so that he will perform
the act himself the sooner. For instance, you may hold
him so that his accidental pawing will be sure to hit the vital
point of the contrivance. But the animal cannot form
an association leading to an act unless the particular im-
pulse to that act is present as an element of the association ;
he cannot supply it from a general stock. The groundwork
of animal associations is not the association of ideas, but
the association of idea or sense-impression with impulse.

In the questionnaire mentioned elsewhere, some questions
were asked with a view to obtaining corroboration or refu-
tation of this theory that an impulse or innervation is a
necessary element in every association formed if that asso-
ciation leads toan act. The questions and answers were :—

Question 1: “If you wanted to teach a horse to tap
seven times with his hoof when you asked him, ‘How many
days are there in a week ?,’ would you teach him by taking
his leg and making him go through the motions ?”

A answered, ‘‘ Yes! at first.”

B answered, ‘‘No! I would not.”

C answered, “At first, yes!”

D answered, ‘‘No!”’

Question 2: “Do you think you could teach him that way,
even if naturally you would take some other way ?”

A answered, ‘‘In time, yes!”

Experimental Study of Associative Processes 107

B answered, “I think it would be a very hard way.”

C answered, ‘“‘Certainly I do.”

D answered, “I do not think I could.”

E answered, “‘ Yes.”

Question 3: “‘How would you teach him ?”

A answered, “I should tap his foot with a whip, so that
he would raise it, and reward him each time.”’

B answered, “‘I should teach him by the motion of the
whip.”

C answered, ‘‘First teach him by pricking his leg the
number of times you wanted his foot lifted.”

D answered, “You put figure 2 on blackboard and touch
him on leg twice with cane, and so on.”

E answered ambiguously.

It is noteworthy that even those who think they could
teach an animal by putting him through the trick do not
use that method, except at first. And what they really do
then is probably to stimulate the animal to the reflex act
of raising his hoof. The hand simply replaces the cane or
whip as the means of stimulus. The answers are especially
instructive, because the numerous counting tricks done by
trained horses seem, at first, to be incomprehensible, unless
the trainer can teach the horse by putting it through the
movement the proper number of times. The counting
tricks performed by Mascot, Professor Maguire’s horse,
were quoted to me by a friend as incomprehensible on my
theory. The answers given above show how simple the
thing really is. All the counting-tricks of all the intelligent
horses depend on the fact that a horse raises his hoof when
a certain stimulus is given. One simple reaction gives the
basis for a multitude of tricks. In the same way other
tricks, which at first sight seem to require that the animal
should learn by being put through the movement, may
depend on some simple reflex or natural impulse.

108 Animal Intelligence

Another question was, ‘“‘How would you teach a cat to
get out of a box, the door of which was closed with a thumb
latch 2?”

A answered, “‘I should use a puffball as a plaything for
the cat to claw at.” This means, I suppose, that he would get
the cat to claw at the puffball and thus direct its clawings
to the vicinity of the thumb piece.

B answered, ‘“‘I would put the cat in and get it good and
hungry and then open the door by lifting the latch with my
finger. ‘Then put some food that the cat likes outside, and
she will soon try to imitate you and so learn the trick.”

C answered, “I would first adjust all things in connection
with the surroundings of the cat so they would be applicable
to the laws of its nature, and then proceed to teach the
tricks?

I suppose this last means that he would fix the box so that
some of the cat’s instinctive acts would lead it to perform
the trick. The answer given by B means apparently that
he would simply leave the thing to accident, for any such
imitation as he supposes is out of the question. At all
events, none of these would naturally start to teach the
trick by putting the animal through the motions, which,
were it a possible way, would probably be a traditional
one among trainers. On the whole, I see in these data no
reason for modifying our dogma that animals cannot learn
acts without the impulse.

Presumably the reader has already seen budding out of
this dogma a new possibility, a further simplification of
our theories about animal consciousness. The possibility
is that animals may have no images or memories at all, no
ideas to associate. Perhaps the entire fact of association
in animals is the presence of sense-impressions with which
are associated, by resultant pleasure, certain impulses,

Experimental Study of Associative Processes 109

and that, therefore, and therefore only, a certain situation
brings forth a certain act. Returning to our analysis of
the association, this theory would say that there was no (9)
or (10) or (3) or (4), that the sense-impression gave rise,
when accompanied by the feeling of discomfort, to the im-
pulse (5) directly, without the intervention of any represen-
tations of the taste of the food, or the experience of being
outside, or the sight of oneself doing the act. This theory
might be modified so as to allow that the representations
could be there, but to deny that they were necessary, were
inevitably present, that the impulse was connected to the
sense-impression through them. It would then claim that
the effective part of the association was a direct bond be-
tween the situation and the impulse, but would not cut off
the possiblity of there being an aura of memories along with
the process. It then becomes a minor question of inter-
pretation which will doubtless sooner or later demand an
answer. I shall not try to answer it now. The more
radical question, the question of the utter exclusion of rep-
resentative trains of thought, of any genuine association
of ideas from the mental life of animals, is worth serious
consideration. I confess that, although certain authentic
anecdotes and certain experiments, to be described soon,
lead me to reject this exclusion, there are many qualities
in animals’ behavior which seem to back it up. If one takes
his stand by a rigid application of the law of parsimony, he
will find justification for this view which no experiments of
mine can overthrow.

Of one thing I am sure, and that is that it is worth while
to state the question and how to solve it, for although the
point of view involved is far removed from that of our lead-
ing psychologists to-day, it cannot long remain so. I am
sorry that I cannot pretend to give a final decision.

ro: Animal Intelligence

The view seems preposterous because, if an animal has
sense-impressions when his brain is excited by currents start-
ing in the end-organs, it seems incredible that he should not
be conscious in imagination and memory by having similar
excitations caused from within. We are accustomed to
think of memory as the companion of sensation. But,
after all, it is a question of fact whether the connections in
the cat brain include connections between present sensation-
neuroses and past sensation-neuroses. The only connec-
tions may be those between the former and impulse-neu-
roses, and there is no authoritative reason why we should
suppose any others unless they are demonstrated by the
cat’s behavior. This is just the point at issue. Such evi-
dence as the phenomena of animals’ dreams does not at all
prove the presence of memory or Imagination. A dog may
very well growl in his sleep without any idea of a hostile
dog. The impulse to growl may be caused by chance ex-
citement of its own neurosis without any sensation-neu-
rosis being concerned. Acts of recognition may have no
feelings of recognition going with or causing them. A
sense-impression of me gets associated in my dog’s mind
with the impulses to jump on me, lick my hand, wag
his tail, etc. If, after a year, the connection between the
two has lasted, he will surely jump on me, lick my hand
and wag his tail, though he has not and never had any
representation of me.

The only logical way to go at this question and settle it
is, I think, to find some associations the formation of which
requires the presence of images, of ideas. You have to give
an animal a chance to associate sense-impression A with
sense-impression B and then to associate B with some act
C so that the presence of B in the mind will lead to the
performance of C. Presumably the representation of B,

Experimental Study of Associative Processes 111

if present, will lead to C just as the sense-impression B did.
Now, if the chance to associate B with A has been improved,
you ought, when the animal is confronted with the sense-
impression A, to get a revival of B and so the act C. Such
a result would, if all chance to associate C with A had been
eliminated, demonstrate the presence of representations
and their associations. I performed such an experiment
in a form modified so as to make it practicable with my
animals and resources. Unfortunately, this modification
spoils the crucial nature of the experiment and robs it of
much of its authority. The experiment was as follows :—

A cat was in the big box where they were kept (see p. 9o)
very hungry. As I had been for a long time the source
of all food, the cats had grown to watch me very carefully.
I sat, during the experiment, about eight feet from the box,
and would at intervals of two minutes clap my hands four
times and say, “‘I must feed those cats.”” Of course the
cat would at first feel no impulse except perhaps to watch me
more closely when this signal was given. After ten seconds
had elapsed I would take a piece of fish, go up to the cage
and hold it through the wire netting, three feet from the
floor. The cat would then, of course, feel the impulse to
climb up the front of the cage. In fact, experience had
previously established the habit of climbing up whenever
I moved toward the cage, so that in the experiment the
cat did not ordinarily wait until I arrived there with the
fish. In this experiment

A = The sense-impression of my movements and voice
when giving the signal.

B = The sense-impression of my movements in taking
fish, rising, walking to box, etc.

C = The act of climbing up, with the impulse leading
thereunto.

ni2 Animal Intelligence

The question was whether after a while A would remind
the cat of B, and cause him to do C before he got the sense-
impression of B, that is, before the ten seconds were up. If
A leads to C through a memory of B, animals surely can
have association of ideas proper, and probably often do.
Now, as a fact, after from thirty to sixty trials, the cat does
perform C immediately on being confronted by A or some
seconds later, at all events before B is presented. And it is
my present opinion that their action is to be explained by
the presence, through association, of the idea B. But it is
not impossible that A was associated directly with the im-
pulse to C, although that impulse was removed from it by
ten seconds of time. Such an association is, it seems to me,
highly improbable, unless the neurosis of A, and with it the
psychosis, continues until the impulse to C appears. But
if it does so continue during the ten seconds, and thus get
directly linked to C, we have exactly a representation, an
image, a memory, in the mind for eight of those ten seconds.
It does not help the deniers of images to substitute an image
of A for an image of B. Yet, unless they do this, they have
to suppose that A comes and goes, and that after ten sec-
onds C comes, and, passing over the intervening blank,
willfully chooses out A and associates itself with it. There
are some other considerations regarding the behavior of the
cats from the time the signal was given till they climbed up,
which may be omitted in the hope that it will soon be pos-
sible to perform a decisive experiment. If an observer can
make sure of the animal’s attention to a sequence A-B,
where B does not arouse any impulse to an act, and then
later get the animal to associate B with C, leaving A out this
time, he may then, if A, when presented anew, arouses C,
bid the deniers of representations to forever hold their
peace.

Experimental Study of Associative Processes 113

Another reason for allowing animals representations and
images is found in the longer time taken to form the associa-
tion between the act of licking or scratching and the con-
sequent escape. If the associations in general were simply
between situation and impulse and act, one would suppose
that the situation would be associated with the impulse to
lick or scratch as readily as with the impulse to turn a button
or claw a string. Such is not the case. By comparing the
curves for Z on pages 57-58 with the others, one sees that for
so simple an act it takes a long time to form the association.
This is not a final reason, for lack of attention, a slight in-
crease in the time taken to open the door after the act was
done, or an absence of preparation in the nervous system
for connections between these particular acts and definite
sense-impressions, may very well have been the cause of the
difficulty in forming the associations. Nor is it certain that
ideas of clawing loops would be easier to form than ideas of
scratching or licking oneself. The matter is still open to
question. But, as said before, my opinion would be that
animals do have representations and that such are the
beginning of the rich life of ideas in man. For the most part,
however, such are confined to specific and narrow practical
lines. There was no evidence that my animals habitually
did form associations of ideas from their experience through-
out, or that such were constantly revived without the spur
of immediate practical advantage.!

1 One result of the application of experimental method to the study of
the intellect of animals was the distinction of learning by the selection of
impulses or acts from learning by the selection of ideas. The usual method
of learning in the case of animals other than man was shown by the studies
reprinted in this volume to be the direct selection, in a certain situation, of
a desirable response and its association with that situation, not the indirect
selection of such a response by the selection of some idea which then of
itself produced the response. The animals did not usually behave as if they

thought of getting freedom or food in a certain way and were thereby moved
I

II4 Animal Intelligence

Before leaving the topic an account may be given of ex-
periments similar to the one described above as performed
on Cats 3 and 4, which were undertaken with Cat 13 and
Dogs 1, 2 and 3.

Cat 13 was fed with pieces of fish at the top of the wire
netting 45 times, to accustom it to climbing up when it saw

to do so, but as if the stimulus in question made immediate connection with
the response itself or an intimately associated impulse.

The experiments had in this respect both a negative or destructive and a
positive or constructive meaning. On the one hand, they showed that animal
learning was not homologous with human association of ideas; that animal
learning was not human learning minus abstract and conceptual thought,
but was on a still ‘lower’ level. On the other hand, the first positive evi-
dence that animals could, under certain circumstances, learn, as man so
commonly does, by the indirect connection of a response with a situation
through some non-sensory relic or representative of the latter, came from my
experiments.

It was perhaps natural that the more exciting denial of habitual learning
by ideas should have attracted more attention than the somewhat tedious
experiments to prove that under certain conditions they could so learn.
At all events, a perverse tradition seems to have grown up to the effect that
I denied the possibility of animals having images or learning in any case by
representative thinking.

There is some excuse for this tradition in the fact that whereas the proof
that the habitual learning of these dogs and cats did not require ‘ideas’
is clear and emphatic, my evidence that certain features of their behavior
did require ‘ideas’ is complicated and imperfect.

The fact seems to be that a ‘free idea’ comes in the animals or in man
only as a result of a somewhat elaborate process of analysis or extraction from
a gross total sensory process. The primary level or grade of experience,
common to animals and little babies, comprises states of mind such as an
adult man gets if lost in anger, fear, suffocation, dyspepsia, looking at a
panorama of unknown objects with head upside down, smelling the mixture
of odors of a soap factory, driving a golf ball, dashing to the net in a game of
tennis, warding off a blow, or swimming under water. For a man to geta
distinct controllable percept of approaching asthma, of a carpet loom seen
upside down, or of a successful ‘carry through,’ or ‘smash’ or ‘lob,’
so that one knows just what one is experiencing or doing, and can recall
just what one experienced or did, requires further experience of the element
in question — contemplation of it in isolation or dealings with it in many varied

Experimental Study of Associative Processes 115

me come with fish. I then went through the same process
as with 3 and 4, but at intervals of 60 to go seconds instead
of 120. After go such trials it occasionally climbed up a
little way, but though 135 trials in all were given, it never
made the uniform and definite reaction which 3 and 4 did.
It reacted, when it reacted at all, at from 5 to 9 seconds after
the signal. Whether age, weight, lack of previous habitual
climbing when I approached, or a slowness in forming the
association made the difference, is uncertain.

Dog 1 was experimented on in the following manner: I
would put him in a big pen, 20-10 feet, and sit outside facing
it, he watching me as was his habit. I would pound with a
stick and say, ‘‘Go over to the corner.” After an interval
(10 seconds for 35 trials, 5 seconds for 60 trials) I would go
over to the corner (12 feet off) and drop a piece of meat
there. He, of course, followed and secured it. On the 6th,

connections. So for a cat to get a distinct controllable percept of a loop,
or of its own clawing or nosing or pulling, it must have the capacity to an-
alyze such elements out of the total gross complexes in which they inhere,
and also certain means or stimuli to such analysis.

This capacity or tendency the cats and dogs do, in my opinion, possess,
though in a far less degree than the average child. They also suffer from
lack of stimuli to the exercise of the capacity. Their confinement, for the
most part, to the direct sensory experience of things and acts, is due in part
to the weakness of the capacity or tendency of their neurones to act in great
detail, and in part to the lack of such stimuli as visual exploration of things
in detail, manual manipulation of the same thing in many ways, and the iden-
tification of elements of objects and acts by language. They get few free
ideas because they are less ready than man to get them under the same con-
ditions and because their instinctive behavior and social environment ofier
conditions that are iess favorable. The task of getting an animal to have
some free ideational representative of a red loop or of pushing up a button
with the nose may be compared with that of getting a very stupid boy to
have a free ideational representative of acceleration, or of the act of sound-
ing th. The difference between them and man which is so emphasized in
the text, though real and of enormous practical importance, is thus not at
all a mysterious gap or trackless desert. We can see our way from animal
to human learning.

116 Animal Intelligence

“th, 16th, 17th, 18th and roth trials he did perform the act
before the 10 seconds were up, then for several times went
during the two-minute intervals without regarding the sig-
nal, and finally abandoned the habit altogether, although
he showed by his behavior when the signal was given that
he was not indifferent to it.

Dogs 1, 2 and 3 were also given 95, 135 and g5 trials, re-
spectively, the acts done being (1) standing up against the
wire netting inclosing the pen, (2) placing the paws on top of
a keg, and (3) jumping up onto a box. The time intervals
were 5 seconds in each case. No dog of these ever per-
formed the act before I started to take the meat to feed
them, but they did show, by getting up if they were lying
down when the signal was given, or by coming to me if they
were in some other part of the pen, that something was sug-
gested to them byit. Why these cases differ from the cases
of Cats 3 and 4 (10 and 12 also presented phenomena like
those reported in the cases of 3 and 4) is an interesting
though not very important question. The dogs were not
kept so hungry as were the cats, and experience had cer-
tainly not rendered the particular impulses involved so
sensitive, so ready to discharge. Dogs 2 and 3 were older.
There is no reason to invoke any qualitative difference in the
mental make-up of the animals until more illuminating ex-
periments are made.

ASSOCIATION BY SIMILARITY AND THE FORMATION
OF CONCEPTS

What there is to say on this subject from the standpoint of
my experiments will be best introduced by an account of
the experiments themselves.

Dog 1 had escaped from AA (O at front) 26 times. He

Experimental Study of Associative Processes 117

was then put in BB (O at back). Now, whereas 2 and 3, who
were put in without previous experience with AA, failed to
paw the loop in BB, No. 1 succeeded. His times were 7.00,
35, 2-05, -40, .32, .10, 1.10, .38, .10, .05, and from then on he
pawed the loop as soon as put in the box. After a day or so
he was put in BBr (O at back high). Although the loop
was in a new position, his times were only .20, .10, .10, etc.
After nine days he was put in a box arranged with a little
wooden platform 23 inches square, hung where the loop was
in BBr. Although the platform resembled the loop not
the least save in position, his times were only .10, .07, .05,
CLC.

lOinB. 7.

12inB.

HinB

Fic. 21.

From the curves given in Figure 21, which tell the history
of 10, 11 and 12 in Br (Oat back) after each had previously
been familiarized with A (O at front), we see this same
influence of practice in reacting to one mechanism upon the
time taken to react to a mechanism at all similar. It natu-
rally takes a cat a longer time to accidentally claw a loop in
the back than in the front, yet a comparison of these curves
with those on page 39, Figure 2, shows the opposite to have
been the case with 10, 11 and 12. The same remarkable

118 Animal Intelligence

quickness was noted in Cats 1 and 3 when put into B (Oat
back) after learning A (O at front). Moreover, the loops
were not alike. The loop in A was of smaller wire, covered
with a bluish thread, while the loop in B was covered with
a black rubber compound, the diameter of the loop being
three times that of A’s loop.

If any advocate of reason in animals has read so far, I
doubt not that his heart has leaped with joy at these two
preceding paragraphs. ‘‘How,” he will say, “can you ex-
plain these facts without that prime factor in human reason,
association by similarity? Surely they show the animal
perceiving likenesses and acting from general ideas.” This
is the very last thing that they show. Let us see why they do
not show this and what they do show. He who thinks that
these animals had a general notion of a loop-like thing as the
thing to be clawed, that they felt the loop in B, different
as it was in size, color and position, to be still a loop, to
have the essential quality of the other, must needs pre-
suppose that the cat has a clear, accurate sensation and
representation of both. Only if the cat discriminates can
it later associate by noticing similarities. This is what such
thinkers do presuppose. A bird, for instance, dives in the
same manner into a river of yellow water, a pond or an ocean.
It has a general notion, they say, of water. It knows that
river water is one thing and pond water another thing, but it
knows that both are water, ergo, fit to dive into. The cat
who reacts to a loop of small wire of a blue color knows
just what that loop is, and when it sees a different loop,
knows its differences, but knows also its likeness, and reacts
to the essential. Thus crediting the cat with our differen-
tiation and perception of individuality, they credit it with
our conceptions and perceptions of similarity. Unless the
animal has the first, there is no reason to suppose the last.

Experimental Study of Associative Processes 119

Now, the animal does not have either. It does not in the first
place react to that particular loop in A, with recognition of
its qualities. It reacts to a vague, ill-defined sense-impres-
sion, undiscriminated and even unperceived in the technical
sense of the word. Morgan’s phrase, ‘‘a bit of pure experi-
ence,” is perhaps as good as any. The loop is to the cat
what the ocean is to a man, when thrown into it when half-
asleep. Thus the cat who climbed up the front of the cage
whenever I said, “‘I must feed those cats,’ would climb up
just as inevitably when I said, ‘‘My name is Thorndike,”
or “To-day is Tuesday.” So cats would claw at the loop
or button when the door was open. So cats would paw at
the place where a loop had been, though none was there.
The reaction is not to a well-discriminated object, but to a
vague situation, and any element of the situation may
arouse the reaction. The whole situation in the case of man
is speedily resolved into elements; the particular elements
are held in focus, and the non-essential is systematically kept
out of mind. In the animal the whole situation sets loose
the impulse; all of its elements, including the non-essen-
tials, get yoked with the impulse, and the situation may be
added to or subtracted from without destroying the asso-
ciation, provided you leave something which will set off
the impulse. The animal does not think one is like the other,
nor does it, as is so often said, mistake one for the other. It
does not think about it at all; it just thinks z/, and the 7¢ is
the kind of ‘‘ pure experience ”’ we have been describing. In
human mental life we“have accurate, discriminated sensa-
tions and perceptions, realized as such, and general notions,
also realized as such. Now, what the phenomena in ani-
mals which we have been considering show is that they
have neither. Far from showing an advanced stage of men-
tality, they show a very primitive and unspecialized stage.

120 3 Animal Intelligence

They are to be explained not by the presence of general no-
tions, but by the absence of notions of particulars. The
idea that animals react to a particular and absolutely de-
fined and realized sense-impression, and that a similar
reaction to a sense-impression which varies from the first
proves an association by similarity, isa myth. We shall see
later how an animal does come in certain cases to discrimi-
nate, in one sense of the word, with a great degree of deli-
cacy, but we shall also see then what must be emphasized
now, that naturally the animal’s brain reacts very coarsely
to sense-Impressions, and that the animal does not think
about his thoughts at all.

This puts a new face upon the question of the origin and
development of human abstractions and consequent general
ideas. It has been commonly supposed that animals had
‘recepts ’ or such semi-abstractions as Morgan’s ‘predomi-
nants,’ and that by associating with these, arbitrary and per-
manent signs, such as articulate sounds, one turned them
into genuine ideas of qualities. Professor James has made
the simple but brilliant criticism that all a recept really
means is a tendency to react in a certain way. But I have
tried to show that the fact that an animal reacts alike to a lot
of things gives no reason to believe that it is conscious of
their common quality and reacts to that consciousness, be-
cause the things it reacts to in the first place are not the
hard-and-fast, well-defined ‘things’ of human life. What
a ‘recept’ or ‘predominan ’ really stands for is no thing
which can be transformed into a notion of a quality by
being labelled with a name. This easy solution of the
problem of abstraction is impossible. A true idea of the
problem itself is better than such a solution.

My statement of what has been the course of develop-
ment along this line is derived from observations of animals’

Experimental Study of Associative Processes 121

behavior and Professor James’ theory of the nature of and
presumable brain processes going with the abstractions and
conceptions of human consciousness, but it is justified chiefly
by its harmony with the view that conception, the faculty
of having general notions, has been naturally selected by
reason of its utility. The first thing is for an animal to learn
to react alike only to things which resemble each other in the
essential qualities. On an artificial, analytic basis, feelings
of abstract qualities might grow out of reacting alike to ob-
jects similar in such a respect that the reaction would be
useless or harmful. But in the actual struggle for existence,
starting with the mammalian mind as we have found it,
you will tend to get reactions to the beneficial similarities
by selection from among these so-called mistakes, before
you get any general faculty of noticing similarities. In
order that this faculty of indifferent reaction to different
things shall grow into the useful faculty of indifferent reac-
tion to different things which have all some quality that makes
the reaction a fit one, there must be a tremendous range of
associations. For a lot of the similarities which are non-
essential have to be stamped out, not by a power of feeling
likeness, but by their failure to lead to pleasure. With
such a wide range of associations we may get reactions on
the one hand where impulses have been connected with one
particular sense-impression because when connected with
all others they had failed to give pleasure, and on the other
hand, reactions where an impulse has been connected with
numerous different impressions possessing one common
quality, and disconnected with all impressions, otherwise
like these, which fail to have that one quality.

Combined with this multiplication of associations, there is,
I think, an equally important factor, the loosening of the
elements of an association from one another and from it as a

122 Animal Intelligence

whole. Probably the idea of the look of the loop or lever or
thumb latch never entered the mind of any one of my cats
during the months that they were with me, except when the
front end of the association containing it was excited by put-
ting the cat into the box. In general, the unit of their con-
sciousness, apart from impulses and emotions, is a whole
association-series. Such soil cannot grow general ideas, for
the ideas, so long as they never show themselves except for
a particular practical business, will not be thought about or
realized in their nature or connections. If enough associa-
tions are provided by a general curiosity, such as is seen
among the monkeys, if the mental elements of the associa-
tion are freed, isolated, felt by themselves, ten a realization
of the ideas, feelings of their similarity by transition from
one to the other, feelings of qualities and of meanings, may
gradually emerge. Language will be a factor in the isola-
tion of the ideas and a help to their realization. But when
any one says that language has been the cause of the change
from brute to man, when one talks as if nothing but it were
needed to turn animal consciousness into human, he is speak-
ing as foolishly as one who should say that a proboscis added
to a cow would make it an elephant.

This is all I have to say, in this connection, about associa-
tion by similarity and conception, and with it is concluded
our analysis of the nature of the association-process in ani-
mals. Before proceeding to treat of the delicacy, com-
plexity, number and permanence of these associations, it
seems worth while to attempt to describe graphically, not by
analysis, the mental fact we have been studying, and also
to connect our results with the previous theories of associa-
tion.

One who has seen the phenomena so far described, who
has watched the life of a cat or dog for a month or more

Experimental Study of Associative Processes 123

under test conditions, gets, or fancies he gets, a fairly defi-
nite idea of what the intellectual life of a cat or dog feels
like. It is most like what we feel when consciousness con-
tains little thought about anything, when we feel the sense-
impressions in their first intention, so to speak, when we feel
our own body, and the impulses we give to it. Sometimes
one gets this animal consciousness while in swimming, for
example. One feels the water, the sky, the birds above, but
with no thoughts about them or memories of how they looked
at other times, or esthetic judgments about their beauty ;
one feels no zdeas about what movements he will make, but
feels himself make them, feels his body throughout. Self-
consciousness dies away. Social consciousness dies away.
The meanings, and values, and connections of things die
away. One feels sense-impressions, has impulses, feels the
movements he makes; that is all.

This pictorial description may be supplemented by an ac-
count of some associations in human life which are learned in
the same way as are animal associations ; associations, there-
fore, where the process of formation is possibly homologous
with that in animals. When a man learns to swim, to play
tennis or billiards, or to juggle, the process is something like
what happens when the cat learns to pull the string to get
out of the box, provided, of course, we remove, in the man’s
case, all the accompanying mentality which is not directly
concerned in learning the feat.!. Like the latter, the former

1 A man may learn to swim from the general feeling, ‘‘I want to be able to
swim.” While learning, he may think of this desire, of the difficulties of the
motion, of the instruction given him, or of anything which may turn up in
his mind. This is all extraneous and is not concerned in the acquisition of
the association. Nothing like it, of course, goes on in the animal’s mind.
Imagine a man thrown into the water repeatedly, and gradually floundering
to the shore in better and better style until finally, when thrown in, he swims
off perfectly, and deprive the man of all extraneous feelings, and you have

124 Animal Intelligence

contains desire, sense-impression, impulse, act and possible
representations. Like it, the former is learned gradually.
Moreover, the associations concerned cannot be formed
by imitation. One does not know how to dive just by see-
ing another man dive. You cannot form them from being
put through them, though, of course, this helps indirectly,
in a way that it does not with animals. One makes use of
no feelings of a common element, no perceptions of simi-
larity. The tennis player does not feel, ‘This ball coming
at this angle and with this speed is similar in angle, though
not in speed, to that other ball of an hour ago, therefore I
will hit it in a similar way.’ He simply feels an impulse
from the sense-impression. Finally, the elements of the
associations are not isolated. No tennis player’s stream of
thought is filled with free-floating representations of any
of the tens of thousands of sense-impressions or move-
ments he has seen and made on the tennis court. Yet there
is consciousness enough at the time, keen consciousness of
the sense-impressions, impulses, feelings of one’s bodily acts.
So with the animals. There is consciousness enough, but
of this kind.

Thus, the associations in human life, which compare with
the simple connections learned by animals, are associations
involving connections between novel, complex and often
inconstant sense-impressions and impulses to acts similarly
novel, complex and often inconstant. Man has the ele-
ments of most of his associations in isolated form, attended
to separately, possessed as a permanent fund, recallable at
will, and multifariously connected among themselves, but
an approximate homologue of the process in animals. He feels discomfort,
certain impulses to flounder around, some of which are the right ones to
move his body to the shore. The pleasure which follows stamps in these,

and gradually the proper movements are made immediately on feeling the
sense-impression of surrounding water.

Experimental Study of Associative Processes 125

with these associations which we have mentioned, and with
others like them, he deals as the animals deal with theirs.
The process, in the man’s mind, leaving out extraneous men-
tal stuff, may be homologous to the association-process in
animals. Of course, by assiduous attention to the elements
of these associations, a man may isolate them, may thus get
these associations to the same plane as the rest. But they
pass through the stage we have described, even then, and
with most men, stay there. The abstraction, the naming,
etc., generally come from observers of the game or action,
and concern things as felt by them, not by the participant.

CRITICISM OF PREVIOUS THEORIES

We may now look for a moment at what previous writers
have said about the nature of association in animals. The
complaint was made early in this book that all the state-
ments had been exceedingly vague and of no value, except as
retorts to the ‘ reason’ school. In the course of the discus-
sion I have tried to extricate from this vagueness definite
statements about imitation, association of ideas, association
by ideas. There is one more theory, more or less hidden in
the vagueness, — the theory that association in animals is the
same as association in man, that the animal mind differs
from the human mind only by the absence of reason and
what it implies. Presumably, silence about what associa-
tion is, means that it is the association which human psy-
chology discusses. When the silence is broken, we get such
utterances of this theory as the following : —

“‘T think we may say then that the higher animals are able
to proceed a long way in the formation and definition of
highly complex constructs, analogous to but probably differ-
ing somewhat from those which we form ourselves. These

126 Animal Intelligence

constructs, moreover, through association with reconstructs,
or representations, link themselves in trains so that a sensa-
tion, or group of sensations, may suggest a series of recon-
structs, or a series of remembered phenomena.” (C. L.
Morgan, Animal Life and Intelligence, p. 341.)

‘Lastly, before taking leave of the subject of the chapter,
Iam most anxious that it should not be thought that, in con-
tending that intelligence is not reason, I wish in any way to
disparage intelligence. Nine tenths at least of the actions of
average men are intelligent and not rational. Do we not all
of us know hundreds of practical men who are in the high-
est degree intelligent, but in whom the rational, analytic
faculty is but little developed? Is it any injustice to the
brutes to contend that their inferences are of the same order
as those of these excellent practical folk? In any case, no
such injustice is intended ; and if I deny them self-conscious-
ness and reason, I grant to the higher animals perceptions
of marvelous acuteness and intelligent inferences of won-
derful accuracy and precision — intelligent inferences in
some cases, no doubt, more perfect even than those of man,
who is often disturbed by many thoughts ” (zbid., pp. 376-
377).

“Language and the analytic faculty it renders possible
differentiate man from the brute”’ (zbid., p. 376).

Here, as elsewhere, it should be remembered that Lloyd
Morgan is not quoted because he is the worst offender or be-
cause he represents the opposite in general of what the pres-
ent writer takes to be the truth. On the contrary, Morgan
is quoted because he is the least offender, because he
has taken the most advanced stand along the line of the
present investigation, because my differences from him are
in the line of his differences from other writers. With the
theory of the passages just quoted, however, which attribute

Experimental Study of Associative Processes 127

extensive association of ideas and general powers compar-
able to those of men minus reason, to the brutes, and which
repeat the time-honored distinction by language, I do not,
in the least, agree. Association in animals does not equal
association in man. The latter is built over and permeated
and transformed by inference and judgment and comparison;
it includes imitation in our narrow sense of transferred
association; it obtains where no impulse is included; it
thus takes frequently the form of long trains of thought
ending in no pleasure-giving act; its elements are often
loose, existing independently of the particular association ;
the association is not only thought, but at the same time
thought about. None of these statements may be truthfully
made of animal association. Only a small part of human
association is at all comparable to it. My opinion of what
that small part is has already been given. Moreover,
further differences will be found as we consider the data
relating to the delicacy, complexity, number, and perma-
nence of associations in animals. I said a while ago that
man was no more an animal with language than an ele-
phant was a cow with a proboscis. We may safely broaden
the statement and say that man 1s not an animal plus rea-
son. It has been one great purpose of this investiga-
tion to show that even after leaving reason out of account,
there are tremendous differences between man and the
higher animals. The problem of comparative psychology is
not only to get human reason from some lower faculties,
but to get human association from animal association.

Our analysis, necessarily imperfect because the first at-
tempted, of the nature of the association-process in animals
is finished, and we have now to speak of its limitations in
respect to delicacy, complexity, number and permanence.

128 Animal Intelligence

DELICACY OF ASSOCIATIONS

It goes without saying that the possible delicacy of asso-
ciations is conditioned by the delicacy of sense-powers. If
an animal doesn’t feel differently at seeing two objects, it
cannot associate one with one reaction, the other with an-
other. An equally obvious factor is attention; what is not
attended to will not be associated. Beyond this there is no
a priort reason why an animal should not react differently
to things varying only by the most delicate difference, and
I am inclined to think an animal could; that any two ob-
jects with a difference appreciable by sensation which are
also able to win attention may be reacted to differently.
Experiments to show this are very tedious, and the practical
question is, ‘‘What will the animal naturally attend to?”
The difficulty, as all trainers say, is to get the animal’s
attention to your signal somehow. Then he will in time
surely react differently, if you give him the chance, to a
figure 7 on the blackboard from the way he does to a figure
8, to your question, ‘“‘How many days are there in a week ?”
and to your question, ‘‘How many legs have you?” The
chimpanzee in London that handed out 3, 4, 5, 6, or 7 straws
at command was not thereby proved of remarkable intelli-
gence or of remarkably delicate associative power. Any
reputable animal trainer would be ashamed to exhibit a
horse who could not do as much ‘ counting’ as that. The
maximum of delicacy in associating exhibited by any animal,
to my knowledge, is displayed in the performance of the dog
‘Dodgerfield,’ exhibited by a Mr. Davis, who brings from
four cards, numbered 1, 2, 3 and 4, whichever one his master
shall think of. That is, you write out an arbitrary list, e.g.
A, 2, 1, 3, 3, 2, 2, I,.4, 2, etc., and hand it to: Mr. Davis, who
looks at the list, thinks of the first number, says ‘‘ Attention !

Experimental Study of Associative Processes 129

Dodger !”’ and then, “Bring it.’ This the dog does and so
on through the list. Mr. Davis makes no signals which any-
one sitting even right beside or in front of him can detect.
Thus the dog exceeds the human observers in delicacy and
associates each with a separate act four attitudes of his mas-
ter, which to human observers seem all alike. Mr. Davis
says he thinks the dog is a mind reader. I think it quite
possible that whatever signs the dog goes by are given un-
consciously and consist only of some very delicate general
differences in facial expression or the manner of saying the
words, ‘‘Bring it,’’ or slight sounds made by Mr. Davis in
thinking to himself the words one or two or three or four.
Mr. Davis keeps his eyes shut and his hands behind a news-
paper. The dog looks directly at his face.

To such a height possible delicacy may attain, but possible
delicacy is quite another thing from actual untrained and
unstimulated delicacy. The difference in reaction has to be
brought about by associating with pleasure the reaction
to the different sense-impression when it itself differs and
associating with pain tendencies to confuse the reactions.
The animal does not naturally as a function of sense-powers
discriminate at all delicately. Thus the cat who climbed
up the wire netting when I said, “I must feed those cats !”
did not have a delicate association of just that act with just
those words. For after I had dropped the clapping part
of the signal and simply used those words, it would react just
as vigorously to the words, ‘To-morrow is Tuesday” or
“My name is Thorndike.’”’ The reaction naturally was to
a very vague stimulus. Taking cat 10 when just beginning
to learn to climb up at the signal, ‘‘I must feed those cats !”’
I started in to improve the delicacy, by opposing to this
formula the formula, ‘‘I will not feed them,” after saying
which, I kept my word. That is, I gave sometimes the

K

130 Animal Intelligence

former signal and fed the cats, sometimes the latter and did
not. The object was to see how long the cat would be in
learning always to go up when I gave the first, never to do
so when I gave thesecond signal. I said the words in both
cases as I naturally would do, so that there was a difference
in emphasis and tone as well as in the mere nature of the
syllables. The two signals were given in all sorts of com-
binations so that there was no regularity in the recurrence of
either which might aid the animal. The cat at first did
not always climb up at the first signal and often did climb
up at the wrong one. The change from this condition to
one of perfect discrimination is shown in the accompanying

curves (Fig. 22), one show-

7 Mn : ing the decrease in fail-

\ at) ures: to cespond:to the

1 @ wrong signal. The first

ee curve is formed by a line

joining the tops of perpendiculars erected at intervals of

1 mm. along the abscissa. The height of a perpendicular

represents the number of times the cat failed to respond

to the food-signal in 20 trials, a height of r mm. being the

representative of one failure. Thus, the entire curve

stands for 280 trials, there being no failures after 60 trials,
and only 1 after the goth.

In the other curve, also, each 1 mm. along the abscissa
stands for 20 trials, and the perpendiculars whose tops the
curve unites represent the number of times the cat in each
20 did climb up at the signal which meant no food. It will
be seen that 380 experiences were necessary before the an-
imal learned that the second signal was different from the
first. ‘The experiment shows beautifully the animal method
of acquisition. If at any stage the animal could have
isolated the two ideas of the two sense-impressions, and felt

Experimental Study of Associative Processes 131

them together in comparison, this long and tedious process
would have been unnecessary.

It might be stated here that the animals also acquired
associations of moderate delicacy in discriminating between
the different boxes. No cat tried to get out of A or B by
licking herself, for instance.

The question may naturally be raised that if naturally
associations are thus vague, the common phenomenon of a
dog obeying his master’s commands, and no one else’s, is
inexplicable. The difference between one man and another,
one voice and another, it may be said, is not much of a dif-
ference, yet is here uniformly discriminated, although we
cannot suppose any such systematic training to reject the
other slightly differing commands. My cats did not so
discriminate. If any one else sat in my chair and called
out, ‘‘I must feed the cats,” they reacted, and probably very
many animals would, if untroubled by emotions of curiosity
or fear at the new individual, go through their tricks as well
at another’s voice as at that of their master. The other
cases exemplify the influence of attention. Repeated
attention to these sense-impressions has rendered them
clear-cut and detailed, and the new impression consequently
does not equal them in calling forth the reaction.

The main thing to carry away from this discussion is
the assurance that the delicacy of the animal in associating
acts with impressions is nothing like the delicacy of the man
who feels that a certain tone is higher, or weight is heavier,
than another, but 7s like the delicacy of the man who runs
to a certain spot to hit one tennis ball and to a different spot
to hit one coming with a slightly different speed.

132 Animal I ntelligence

COMPLEXITY OF ASSOCIATIONS

An important question, especially if one wishes to rate an
animal on a scale of intelligence, is the question of how com-
plex an association it can form. A man can learn that to
open a door he has to put the key in its hole, turn it, turn
the knob, and pull the door. Here, then, is a complex act
connected with the simple sense-impression. Or, con-
versely, a man knows that when the ringing of a bell is
followed by a whistle and that by a red light he is to doa
certain thing, while if any of the three happens alone, he is
not to. How far, then, we ask, can animals go along the
line of increased complexity in the associations ?

We must not mistake for a complex association a series
of associations, where one sense-impression leads to an act
such as to present a new sense-impression which leads to
another act which in its turn leads to a new sense-impression.
Of the formation of such series animals are capable to a
very high degree. Chicks from 10 to 25 days old learned to
go directly through a sort of big labyrinth requiring a series
of 23 distinct and in some cases fairly difficult associations,
of which 11 involved choices between two paths. By this
power of acquiring a long series animals find their way to
distant feeding grounds and back again. But all such cases
are examples of the number, not of the complexity, of animal
associations.

Some of my boxes were such as did give a chance for a
complex association to be formed. Such were G (thumb
latch), J (double), K and L (triples) for the cats, and O (triple)
for the dogs. It would be possible for a cat, after stepping
on the platform in K, to notice that the platform was in a
different position, and so feel then a different sense-impres-
sion from before, and thus turn the thing into a serial asso-

Experimental Study of Associative Processes 133

ciation. The cat would then be like a man who on seeing
a door should feel only the impulse to stick the key in the
hole, but then, seeing the door plus a key in the hole, should
feel the impulse to turn the key and so on through. My
cats did not give any signs of this, so that with them it was
either a complex association or an irregular happening of
the proper impulses. Probably the same was the case with
Dog 1. Cats 10, 11, 12 in L knew all the movements
separately before being experimented on with the combina-
tion. Cats 2, 3, 4 had had some experience of D, which
worked by a string something like the string partof K. The
string in K was, however, quite differently situated and
required an altogether different movement to pullit. Since
further No. 2, who had had ten times as much experience
in D as 3 or 4, succeeded no better with the string element
of K than they, it is probable that the experience did not
help very much. All else in all these compound associations
was new. At the same time the history of these animals’
dealings with these boxes would not fairly represent that of
animals without general experience of clawing at all sorts
of loose or shaky things in the inside of a box. These
cats had learned to claw at all sorts of things. The
time-curves were taken as in the formation of the other
associations, and, in addition, the order in which the animal
did the several things required was recorded in every trial.

In the case of all the curves, except the latter part of 3
in G, one notices a very gradual slope and an excessive
irregularity in the curve throughout. Within the limits
of the trials given the animals are unable to form a perfect
association and what advancement they make is very slow.
The case of 3 in G is not an exception to this, but a proof of
it. For 3 succeeded in making a perfect association, by
accidentally hitting on a way to turn the compound asso-

134 Animal Intelligence

ciation into a simple one. He happened one time to paw
down the thumb piece at the same time that his other
fore limb, with which he was holding on between the door
and the top of the box, was pressing against the door.
This giving him success he repeated it in later trials and in a
short time had it fixed as an element in a perfect association.
The marked change in his curve, from an irregular and grad-
ual slope at such a height as displayed a very imperfect
association, to a constant and very slight height, shows pre-
cisely the change from a compound to a simple association.

Compound associations are formed slowly and not at all
well. Further observation shows that they were really not
formed at all. For the animals did not, except 3 in K for a
certain period, do the several things in a constant order, nor
did they do them only once apiece. On the contrary, an
animal would pull the string several times after the bolt
had gone up with its customary click, and would do some-
times one thing first, sometimes another. It may also be
noted here, in advance of its proper place, that these com-
pound associations are far below the simple in point of
permanence. The conduct of the animals is clearly not
that of minds having associated with a certain box’s interior
the idea of a succession of three movements. The animal
does not feel, “‘I did this and that and that and got out,”
or, more simply still, “‘this and that and that means getting
out.” If it did, we should soon see it doing what was
necessary without repetition and in a fairly constant time.

I imagine, however, that an animal could learn to associ-
ate with one sense-impression a compound act so as to
perform its elements in a regular order. By arranging
the box so that the second and third elements of the act
could be performed only after the first had been, and the
third only after the first and second, I am inclined to think

Experimental Study of Associative Processes 135

you could get a very vigorous cat to learn the elements in
order and form the association perfectly. The case is
comparable to that of delicacy. The cat does not tend to
know what he is doing or to depart from the hit-or-miss
method of learning, but by associating the other combina-
tions of elements with failure to get pleasure, as in delicacy
experiments we associated the reactions to all but the one
signal, you could probably stamp out all but the 1, 2, 3
order.

The fact that you have to thus maneuver to get the
animals to have the three impulses in a regular order shows
that even when they are so, there is no idea of the three as
in an order, no thinking about them. Representations do
not get beyond their first intention. They are not carried
up into a free life which works them over anew. A complex
act does not imply a complex thought, or, more exactly, a
performance of a series does not imply the thought of a
series. Consequently, since the complexity of the act
depends on the power which failure has to stamp out all
other combinations, it is far more limited than in man.

NUMBER OF ASSOCIATIONS

The patent and important fact is that there are so few in
animals compared to the human stock. Even after taking
into account the various acts associated with various
smells, and exaggerating the possibility of getting an equip-
ment of associations in this field which man lacks, one must
recognize how far below man any animal is in respect to
mere quantity of associations. ‘The associations with words
alone of an average American child of ten years far out-
number those of any dog. A good billiard player probably
has more associations in connection with this single pas-

136 Animal Intelligence

time than a dog with his whole life’s business. In the asso-
ciations which are homologous with those of animals man
outdoes them and adds an infinity of associations of a
different sort. The primates would seem, by virtue of their
incessant curiosity and addition to experience not for any
practical purpose but merely for love of mental life, to
represent an advanced stage toward this tremendous
quantity of associations. In man not only this activity
and curiosity, but also education, increases the number of
associations. Associations are formed more quickly, and
the absence of need for self-support during a long infancy
gives time. Associations thus formed work back upon
practical life, and by showing better ways decrease the
need of work, and so again increase the chance to form
associations. The result in the case of a human mind to-
day is the possession of a thesaurus of valuable associations,
if the time has been wisely spent. The free life of ideas,
imitation, all the methods of communication, and the
original accomplishments which we may include under the
head of invention, make the process of acquisition in many
cases quite a different one from the trial and error method
of the animals, and in general much shorten it.

Small as it is, however, the number of associations which
an animal may acquire is probably much larger than popu-
larly supposed.

My cats and dogs did not mix up their acts with the
wrong sense-impressions. The chicks that learned the
series of twenty-three associations did not find it a task
beyond their powers to retain them. Several three-day-old
chicks, which I caused to learn ten simple associations in
the same day, kept the things apart and on the next morning
went through each act at the proper stimulus. In the hands
of animal trainers some animals get a large number of

Experimental Study of Associative Processes 137

associations perfectly inhand. The horse Mascot is claimed
to know the meaning of fifteen hundred signals! He
certainly knows a great many, and such as are naturally
difficult of acquisition. It would be an enlightening
investigation if some one could find out just how many
associations a cat or dog could form, if he were carefully
and constantly given an opportunity. The result would
probably show that the number was limited only by the
amount of motive available and the time taken to acquire
each. For there is probably nothing in their brain structure
which limits the number of connections that can be formed,
or would cause such connections, as they grew numerous,
to become confused.

In their anxiety to credit animals with human powers,
the psychologists have disregarded or belittled, perhaps,
the possibilities of the strictly animal sort of association.
They would think it more wonderful that a horse should
respond differently to a lot of different numbers on the black-
board than that he should infer a consequence from prem-
ises. But if it be made a direct question of pleasure or
pain to an animal, he can associate any number of acts with
different stimuli. Only he does not form any associations
until he has to, until the direct benefit is apparent, and, for
his ordinary life, comparatively few are needed.

On the whole our judgment from a comparison of man’s
associations with the brutes’ must be that a man’s are nat-
urally far more delicate, complex and numerous, and that
in as far as the animals attain delicacy, complexity, or a
great number of associations, they do it by methods which
man uses only in a very limited part of the field.

138 Animal Intelligence

PERMANENCE OF ASSOCIATIONS

Once formed, the connections by which, when an animal
feels a certain sense-impression, he does a certain thing,
persist over considerable intervals of time. With the curves
on pages 39 to 58 and 60 to 65 are given in many instances 4
additional curves showing the animal’s proficiency after an
interval without experience. To these data may be added
the following : —

The three chicks that had learned to escape through
the long labyrinth (involving twenty-three associations)
succeeded in repeating the performance after ten days’
interval. Similarly the chicks used as imitators in V, W, X
and Y did not fail to perform the proper act after an in-
terval of twenty days. Cat 6, who had had about a hundred
experiences in C (button), had the association as perfect after
twenty days as when it left off. Cat 2, who had had 36 ex-
periences with C and had attained a constant time of 8 sec-
onds, escaped fourteen days later in 3, 9 and 8 seconds, re-
spectively, in three trials. Cat 1, after an interval of twenty
days, failed in 10 minutes to escape from C. The signal
for climbing up the front of the cage was reacted to by No. 3
after an interval of twenty-four days. No. 10, who had
learned to discriminate between ‘I must feed those cats’
and ‘I will not feed them,’ was tried after eighty days. It
was given 50 trials with the second signal mingled indiscrim-
inately with 25 trials with the first. I give the full record of
these, ‘yes’ equalling a trial in which she ‘forgot’ and
climbed up, ‘no’ equalling a trial in which she wisely stayed
down. Dashes represent intervening trials with the first

1See roin A, 3in A, 1oinD; roinC,4inC,3inC; 6, 2,5,4in E; 4in

F; roinH,3inH; 3,4,5,inI; 4inG,3inG;3inK; 1roinL; dogrinN
and CC; dog: in Gand O.

Experimental Study of Associative Processes 139

signal, to which she always reacted. It will be observed
that 50 trials put the cat in the same position that 350 had
done in her first experience, although in that first experience
she had had only about a hundred trials after the association
had been perfected. The association between the first
signal and climbing up was perfect after the eighty days.

TABLE 8

TRIALS 1-7 | TRIALS 8-17 | TRIALS 18-27] TRIALS 28-35 | TRIALS 36-42 | TRIALS 43-50

— yes no SSS a —
— yes yes — no —
yes yes no — no —
yes — no no — ——
nO” 4 yes — no no —
—- yes = yes no no
yes no yes no no no
yes yes yes —— —— yes
no no yes no — no
no yes yes no no
— no no no no
— yes no no no
aa yes no

All these data show that traces of the connections once
formed are very slow in being lost. If we allow that part
of the time in the first trial in all these cases is due to the
time taken to realize the situation (time not needed in the
trials when the association is forming and the animal is
constantly being dropped into boxes), we may say that the
association is as firm as ever for a considerable time after
practice at it is stopped. How long a time would be re-
quired to annul the influence of any given quantity of
experience, say of an association which had been gone
through with ten times, Icannotsay. It could, if profitable,

140 Animal Intelligence

easily be determined in any case. The only case of total
loss of the association (No. 1 in C) is so exceptional that I
fancy something other than lapse of time was its cause.
The main interest of these data, considered as quantitative
estimates, is not psychological, but biological. They show
what a tremendous advantage the well-developed associa-
tion-process is to an animal. The ways to different feeding
grounds, the actions of enemies, the appearance of noxious
foods, are all connected permanently with the proper re-
action by a few experiences which need be reénforced only
very rarely. Of course, associations without any perma-
nence would be useless, but the usefulness increases im-
mensely with such a degree of permanence as these results
witness. An interesting experiment from the biological
point of view would be to see how infrequently an experience
could occur and yet lead eventually to a perfect association.
An experiment approximating this is recorded in the time-
curves for Box H in Figure 7, on page 47. Three trials at a
time were given, the trials being two or three days apart.
As may be seen from the curves, the association was readily
formed.

The chief psychological interest of these data is that they
show that permanence of associations 7s not memory. The
fact that a cat, when after an interval she is put into box G,
proceeds to immediately press the thumb piece and push
the door, does not at all mean that the cat feels the box
to be the same from which she weeks ago freed herself by
pushing down that thumb piece, or thinks about ever
having felt or done anything in that box. She does not
refer the present situation to a situation of the past and real-
ize that it is the same, but simply feels on being confronted
with that situation the same impulse which she felt before.
She does the thing now for just the same reason that she

Experimental Study of Associative Processes 141

did it before, namely, because pleasure has connected that
act above all others with that sense-impression, so that it
is the one she feels like doing. Her condition is that of the
swimmer who starts his summer season after a winter’s
deprivation. When he jumps off the pier and hits the water,
he swims, not because he remembers that this is the way he
dealt with water last summer and so applies his remembrance
to present use, but just because experience has taught him
to feel like swimming when he hits the water. All talk
about recognition and memory in animals, if it asserts the
presence of anything more than this, is a gross mistake.
For real memory is an absolute thing, including everything
but forgetfulness. If the cat had real memory, it would,
when after an interval dropped into a box, remember that
from this box it escaped by doing this or that and conse-
quently, either immediately or after a time of recollection,
go do it, or else it would not remember and would fail
utterly to do it. On the contrary, we have all grades of
partial ‘forgetfulness,’ just like the grades of swimming one
might find if he dropped a dozen college professors into the
mill ponds of their boyhood, just like the grades of forget-
fulness of the associations once acquired on the ball field
which are manifested when on the Fourth of July the
‘solid men’ of a town get out to amuse their fellow citizens.
The animal makes attacks on a spot around the vital one,
or claws at the thing — but not so precisely as before, or
goes at it a while and then resorts to instinctive methods
of getting out. Its actions are exactly what would be
expected of an animal in whom the sense-impression aroused
the impulse imperfectly, or weakly, or intermittently, but
are not at all like the actions of one who felt, “I used to
get out of this box by pulling that loop down.” In fact,
the record of No. 10 given on page 139 seems to be final on

142 Animal Intelligence

this point. If at any time in the course of the 50 trials it
had remembered that ‘I will not feed them’ meant ‘no fish,’
it would thenceforth have failed to react. It would have
stopped short in the ‘yes’ reactions, instead of gradually
decreasing their percentage. ‘Memory’ in animals, if one
still chooses to use the word, is permanence of associations,
not the presence of an idea of an experience attributed to
the past.

To this proposition two corollaries may be added. First,
these phenomena of incomplete forgetfulness extend the
evidence that animals do not have a stock of independent
ideas, the return of which, plus past associates, equals
memory. Second, there is, properly speaking, no continuity
in their mental streams. The present thought does not
clutch the past to its bosom or hold the future in its womb.
The animal’s self is not a being ‘looking before and after,’
but a direct practical association of feelings and impulses.
So far as experiences come continuously, they may be said
to form a continuous mental life, but there is no continuity
imposed from within. The feelings of its own body are
always present, and impressions from outside may come as
they come to us. When the habit of attending to the
elements of its associations and raising them up into the
life of free ideas is acquired, these permanent bodily associa-
tions may become the basis of a feeling of self-hood and the
trains of ideas may be felt as a continuous life.

INHIBITION OF INSTINCTS BY HABIT

One very important result of association remains to be
considered, its inhibition of instincts and previous associa-
tions. An animal who has become habituated to getting
out of a box by pulling a loop and opening the door will

Experimental Study of Associative Processes 143

do so even though the hole in the top of the box be uncov-
ered, whereas, if, in early trials, you had left any such hole,
he would have taken the instinctive way and crawled
through it. Instances of this sort of thing are well-nigh
ubiquitous. It is a tremendous factor in animal life,
and the strongest instincts may thus be annulled. The
phenomenon has been already recognized in the literature
of the subject, a convenient account being found in James’
‘Psychology,’ Vol. II, pages 394-397. In addition to such
accounts, one may note that the influence of association is
exerted in two ways. The instinct may wane by not being
used, because the animal forms the habit of meeting the
situation in a different way, or it may be actually inhibited.
An instance of the former sort is found in the history of
a cat which learns to pull a loop and so escape from a box
whose top is covered by a board nailed over it. If, after
enough trials, you remove a piece of the board covering
the box, the cat, when put in, will still pull the loop instead
of crawling out through the opening thus made. But, at
any time, if she happens to notice the hole, she may make
use of it. An instance of the second sort is that of a chick
which has been put on a box with a wire screen at its edge,
preventing her from jumping directly down, as she would
instinctively do, and forcing her to jump to another box on
one side of it and thence down. In the experiments which
I made, the chick was prevented by a second screen from
jumping directly from the second box also. That is, if in
the accompanying figure, A is a box 34 inches high, B a box
25 inches high, C a box 16 inches high, and D the pen with
the food and other chicks, the subject had to go A~-B-C-
D. The chick tried at first to get through the screen,
pecked at it and ran up and down along it, looking at the
chicks below and seeking for a hole to get through. Finally

-

144 Animal Intelligence

it jumped to B and, after a similar process, to C. After
enough trials it forms the habit and when put on A goes
immediately to B, then
to C and down. Now
if, after 75 or 80 trials,
you take away the
screens, giving the chick
a free chance to go to D
from either A or B, and
then put it on A, the
following phenomenon
appears. The chick goes
up to the edge, looks over, walks up and down it for a while,
still looking down at the chicks below, and then goes and
jumps to B as habit has taughtittodo. The same actions
take place on B. No matter how clearly the chick sees
the chance to jump to D, it doesnot doso. Theimpulse has
been truly inhibited. It is not the mere habit of going the
other way, but the impossibility of going that way. In one
case I observed a chick in whom the instinct was all but, yet
not quite, inhibited. When tried without the screen, it went
up to the edge to look over nine times, and at last, after
seven minutes, did jump straight down.

FIG. 23.

ATTENTION

I have presupposed throughout one function which it
will be well to now recognize explicitly, attention. As
usual, attention emphasizes and facilitates the process
which it accompanies. Unless the sense-impression is
focussed by attention, it will not be associated with the
act which comes later. Unless two differing boxes are at-

tended to, there will be no difference in the reactions to

Experimental Study of Associative Processes 145

them. The really effective part of animal consciousness,
then, as of human, is the part which is attended to; at-
tention is the ruler of animal as well as human mind.

But in giving attention its deserts we need not forget
that it is not here comparable to the whole of human at-
tention. Our attention to the other player and the ball
in a game of tennis zs like the animal’s attention, but our
attention to a passage in Hegel, or the memory which
flits through our mind, or the song we hear, or the player
we idly watch, is mot. There ought, I think, to be a separate
name for attention when working for immediate practical
associations. It is a different species from that which
holds objects so that we may define them, think about them,
remember them, etc., and the difference is, as our previous
sentence shows, not that between voluntary and involun-
tary attention. The cat watching me for signs of my walk-
ing to the cage with fish is not in the condition of the man
watching a ball game, but in that of the player watching
the ball speeding toward him. There is a notable difference
in the permanence of the impression. The man watching
the game can remember just how that fly was hit and how
the fielder ran for it, though he bestowed only a slight
quantity of attention on the matter, while the fielder may
attend to the utmost to the ball and yet not remember at
all how it came or how he ran forit. The one sort of atten-
tion leads you to think about a thing, the other to act with
reference to it. We must be careful to remember that
when we say that the cat attended to what was said, we
do not mean that he thereby established an idea of it.
Animals are not proved to form separate ideas of sense-
impressions because they attend to them, for the kind of
attention they give is the kind which, when given by men,

results in practical associations, not in establishing ideas
j

146 Animal Intelligence

of objects. If attention rendered clear the idea, we should
not have the phenomena of incomplete forgetfulness lately
mentioned. The animal would get a definite idea of just
the exact thing done and would do it or nothing. The
human development of attention is in closest connection
with the acquisition of a stock of free ideas.

SOCIAL CONSCIOUSNESS

Besides attention there is another topic somewhat apart
from our general one, which yet deserves a few words. It
concerns animals’ social consciousness, their consciousness
of the feelings of their fellows. Do animals, for example,
when they see others feeding, feel that the others are feeling
pleasure? Do they, when they fight, feel that the other
feels pain? So level-headed a thinker as Lloyd Morgan has
said that they do, but the conduct of my animals would
seem to show that they did not. For it has given us good
reason to suppose that they do not possess amy stock of iso-
lated ideas, much less any abstracted, inferred, or transferred
ideas. These ideas of others’ feelings imply a power to trans-
fer states felt in oneself to another and realize them as there.
Now it seems that any ability to thus transfer and realize
an idea ought to carry with it an ability to form a trans-
ferred association, toimitate. If the animal realizes the men-
tal states of the other animal who before his eyes pulls the
string, goes out through the door, and eats fish, he ought to
form the association, ‘impulse to pull string, pleasure of
eating fish.’ This we saw the animal could not do.

In fact, pleasure in another, pain in another, is not a
sense-presentation or a representation or feeling of an ob-
ject of any sort, but rather a ‘meaning,’ a feeling ‘of the
fact that.’ It can exist only as something thought about.

Experimental Study of Associative Processes 147

It is never ‘a bit of direct experience,’ but an abstraction
from our own life referred to that of another.

I fancy that these feelings of others’ feelings may be con-
nected pretty closely with imitation, and for that reason
may begin to appear in the monkeys. There we have some
fair evidence for their presence in the tricks which monkeys
play on each other. Such feelings seem the natural explana-
tion of the apparently useless tail-pullings and such like
which make up the attractions of the monkey cage. These
may, however, be instinctive forms of play-activity or
merely examples of the general tendency of the monkeys
to fool with everything.

INTERACTION

T hope it will not be thought impertinent if from the stand-
point of this research I add a word about a general psycho-
logical problem, the problem of interaction. I have spoken
all along of the connection between the situation and a cer-
tain impulse and act being stamped in when pleasure results
from the act and stamped out when it doesn’t. In this fact,
which is undeniable, lies a problem which Lloyd Morgan
has frequently emphasized. How are pleasurable results able
to burn in and render predominant the association which led to
them? ‘This is perhaps the greatest problem of both human
and animal psychology. Unfortunately in human psy-
chology it has been all tangled up with the problems of free
will, mental activity, voluntary attention, the creation of
novel acts, and almost everything else. In our experiments
we get the data which give rise to the problem, in a very
elementary form.

It should first be noted about the fact that the pleasure
does not burn in an impulse and act themselves, but an im-

148 Animal Intelligence

pulse and act as connected with that particular situation. No
cat ever goes around clawing, clawing, clawing all the time,
because clawing in these boxes has resulted in pleasure.
Secondly, the connection thus stamped in is not contem-
poraneous, but prior to the pleasure. So much for the fact;
now for the explanation. I do not wish to rehearse or add
to the arguments with which so many pages have been al-
ready filled by scientists and philosophers both. What we
need most is not argument, but accurate accounts of the
mental fact and of the brain-process. But I do wish to say
to the parallelist, what has not to my knowledge been said,
that 1f he presupposes, to account for this fact, a ‘ physical
analogue of the hedonic consciousness,’ it is his bounden
duty to first show how any motion in any neurone or group
of neurones in the nervous system can possess this power of
stamping in any current which causesit. For no one would,
from our present knowledge of the brain, judge a priori that
any motion in any part of it could be conceived which should
be thus regnant over all the others. And next he must show
the possibility of the current which represents the associa-
tion being the excitant of the regnant motion in a manner
direct enough for the purpose.

I wish also to say that whoever thinks that, going along
with the current which parallels the association, there is an
accompanying minor current, which parallels the pleasure
and which stamps in the first current when present with it,
flies directly in the face of the facts. There is no pleasure
along with the association. The pleasure does not come until
after the association is done and gone. It is caused by no
such minor current, but by the excitation of peripheral
sense-organs when freedom from confinement is realized or
food is secured. Of course, the notion of such a secondary
subcurrent is mythology, anyway.

Experimental Study of Associative Processes 149

To the interactionist I would say: ‘‘Do not any more
repeat in tiresome fashion that consciousness does alter
movement, but get to work and show when, where, in what
forms and to what degrees it doesso. Then, even if it turns
out to have been a physical parallel that did the work, you
will, at least, have the credit of attaining the best knowledge
about the results and their conditions, even though you mis-
named the factor.”

Besides this contribution to general psychology, I think
we may safely offer one to pedagogical science. At least
some of our results possess considerable pedagogical inter-
est. The fundamental form of intellection, the association-
process in animals, is one, we decided, which requires the
personal experience of the animal in all its elements. The
association cannot be taught by putting the animal through
it or giving it a chance to imitate. Now every observant
teacher realizes how often the cleverest explanation and the
best models for imitation fail. Yet often, in such cases, a
pupil, if somehow enticed to do the thing, even without
comprehension of what it means, even without any real
knowledge of what he is doing, will finally get hold of it.
So, also, in very many kinds of knowledge, the pupil who
does anything from imitation, or who does anything from
being put through it, fails to get a real and permanent mas-
tery of the thing. I am sure that with a certain type of
mind the only way to teach fractions in algebra, for example,
is to get the pupil to do, do, do. Iam inclined to think that
in many individuals certain things cannot be learned save by
actual performance. And I think it is often a fair question,
when explanation, imitation and actual performance are all
possible methods, which is the best. We are here alongside
the foundations of mental life, and this hitherto unsuspected
law of animal mind may prevail in human mind to an extent

150 Animal Intelligence

hitherto unknown. The best way with children may often
be, in the pompous words of an animal trainer, ‘to arrange
everything in connection with the trick so that the animal
will be compelled by the laws of his own nature to perform
ats”

This does not at all imply that I think, as a present school
of scientists seem to, that because a certain thing kas been in
phylogeny we ought to repeat it in ontogeny. Heaven
knows that Dame Nature herself in ontogeny abbreviates
and skips and distorts the order of the appearance of organs
and functions, and for the best of reasons. We ought to
make an effort, as she does, to omit the useless and anti-
quated and get to the best and most useful as soon as possible ;
we ought to change what zs to what ought to be, as far as we
can. And I would not advocate this animal-like method of
learning in place of the later ones unless it does the same
work better. I simply suggest that in many cases where
at present its use is never dreamed of, it may be a good
method. As the fundamental form of intellection, every
student of theoretical pedagogy ought to take it into account.

There is one more contribution, this time to anthropology.
If the method of trial and error, with accidental success, be
the method of acquiring associations among the animals, the
slow progress of primitive man, the long time between stone
age and iron age, for instance, becomes suggestive. Primi-
tive man probably acquired knowledge by just this process,
aided possibly by imitation. At any rate, progress was not
by seeing through things, but by accidentally hitting upon
them. Very possibly an investigation of the history of
primitive man and of the present life of savages in the light
of the results of this research might bring out old facts in a
new and profitable way.

Comparative psychology has, in the light of this research,

Experimental Study of Associative Processes 151

two tasks of prime importance. One is to study the passage
of the child mind from a life of immediately practical associa-
tions to the life of free ideas; the other is to find out how far
the anthropoid primates advance toward a similar passage,
and to ascertain accurately what faint beginnings or prepara-
tions for such an advance the early mammalian stock may
be supposed to have had. In this latter connection I think
it will be of the utmost importance to bear in mind the pos-
sibility that the present anthropoid primates may be men-
tally degenerate. ‘Their present aimless activity and inces-
sant, but largely useless, curiosity may be the degenerated
vestiges of such a well-directed activity and useful curios-
ity as led homo sapiens to important practical discoveries,
such as the use of tools, the art of making fire, etc. It is
even a remote possibility that their chattering is a relic
of something like language, not a beginning of such. Com-
parative psychology should use the phenomena of the
monkey mind of to-day to find out what the primitive mind
from which man’s sprung off was like. That is the impor-
tant thing to get at, and the question whether the present
monkey mind has not gone back instead of ahead is an all-
important question. A natural and perhaps sufficient cause
of degeneracy would be arboreal habits. The animal that
found a means of survival in his muscles might well lose the
means before furnished by his brain.

To these disconnected remarks still another must be added,
addressed this time to the anecdote school. Some member
of it who has chanced to read this may feel like saying:
“This experimental work is all very well. Your cats and
dogs represent, it is true, specimens from the top stratum
of animal intelligence, and your negations, based on their
conduct, may be authoritative so far as concerns the
average, typical mammalian mind. But our anecdotes

152 Animal Intelligence

do not claim to be stories of the conduct of the average
or type, but of those exceptional individuals who have
begun to attain higher powers. And, if even a few
dogs and cats have these higher powers, our contention
is, in a modified form, upheld.” To all this I agree,
provided the anecdote school now realize just what
sort of a position they hold. They are clearly in pretty
much the same position as spiritualists. ‘Their anecdotes
are on pretty much the same level as the anecdotes of
thought-transference, materializations of spirits, super-
normal knowledge, etc. Not in quite the same position, for
far greater care has been given by the Psychical Research
Society to establishing the criteria of authenticity, to insur-
ing good observation, to explaining by normal psychology
all that can be so explained, in the case of the latter than
the anecdote school has done in the case of the former. The
off-hand explanation of certain anecdotes by invoking rea-
son, or imitation, or recognition, or feelings of qualities, is
on a par with the explanation of trance-phenomena and such
like by invoking the spirits of dead people. I do not deny
that we may get lawfully a supernormal psychology, or
that the supernormal acts it finds may turn out to be ex-
plained by these functions which I have denied to the nor-
mal animal mind. But I must soberly declare that I think
there is less likelihood that such functions are the explana-
tion of animal acts than that the existence of the spirits of
dead people is the true explanation of the automatisms of
spiritualistic phenomena. So much for the anecdote school,
if it calls itself by its right name and pretends only to give
an abnormal animal psychology. ‘The sad fact has been that
it has always pushed forward these exceptions as the essen-
tial phenomena of animal mind. It has built up a general
psychology from abnormal data. It is like an anatomy
written from observations on dime-museum freaks.

Experimental Study of Associative Processes 153

CONCLUSION

I do not think it is advisable here, at the close of this
paper, to give a summary of its results. The paper itself
is really only such a summary with the most important evi-
dence, for the extent of territory covered and the need of
brevity have prevented completeness in explanation or il-
lustration. If the reader cares here, at the end, to have the
broadest possible statement of our conclusions and will take
the pains to supply the right meaning, we might say that
our work has described a method, crude but promising, and
has made the beginning of an exact estimate of just what
associations, simple and compound, an animal can form,
how quickly he forms them, and how long he retains them.
It has described the method of formation, and, on the con-
dition that our subjects were representative, has rejected
reason, comparison or inference, perception of similarity,
and imitation. It has denied the existence in animal con-
sciousness of any important stock of free ideas or impulses,
and so has denied that animal association is homologous
with the association of human psychology. It has homolo-
gized it with a certain limited form of human association. It
has proposed, as necessary steps in the evolution of human
faculty, a vast increase in the number of associations, signs
of which appear in the primates, and a freeing of the ele-
ments thereof into independent existence. It has given us
an increased insight into various mental processes. It has
convinced the writer, if not the reader, that the old specula-
tions about what an animal could do, what it thought,
and how what it thought grew into what human beings
think, were a long way from the truth, and not on the road
to it.

Finally, I wish to say that, although the changes proposed

154 Animal Intelligence

in the conception of mental development have been sug-
gested somewhat fragmentarily and in various connections,
that has not been done because I think them unimportant.
On the contrary, I think them of the utmost Importance. I
believe that our best service has been to show that animal
intellection is made up of a lot of specific connections, whose
elements are restricted to them, and which subserve practi-
cal ends directly, and to homologize it with the intellection
involved in such human associations as regulate the conduct
of a man playing tennis. The fundamental phenomenon
which I find presented in animal consciousness is one which
can harden into inherited connections and reflexes, on the
one hand, and thus connect naturally with a host of the
phenomena of animal life; on the other hand, it emphasizes
the fact that our mental life has grown up as a mediation be-
tween stimulus and reaction. The old view of human con-
sciousness is that it is built up out of elementary sensations,
that very minute bits of consciousness come first and grad-
ually get built up into the complex web. It looks for the
beginnings of consciousness to /ittle feelings. This our view
abolishes and declares that the progress is not from little and
simple to big and complicated, but from direct connections to
indirect connections in which a stock of isolated elements plays
a part, is from ‘ pure experience’ or undifferentiated feelings,
to discrimination, on the one hand, to generalizations, ab-
stractions, on the other. If, as seems probable, the primates
display a vast increase of associations, and a stock of free-
swimming ideas, our view gives to the line of descent a mean-
ing which it never could have so long as the question was
the vague one of more or less ‘ intelligence.’ It will, I hope,
when supported by an investigation of the mental life of
the primates and of the period in child life when these di-
rectly practical associations become overgrown by a rapid

Experimental Study of Associative Processes 155

luxuriance of free ideas, show us the real history of the
origin of human faculty. It turns out apparently that
a modest study of the facts of association in animals
has given us a working hypothesis for a comparative

psychology. —

CHAPTER IIT

THE INSTINCTIVE REACTIONS OF YouNG Caicxs!

THE data to be presented in this article were obtained in
the course of a series of experiments conducted in connec-
tion with the psychological laboratory of Harvard Univer-
sity during the year 1896-1897. About sixty chicks were
used as subjects. In general their experiences were entirely
under my control from birth. Where this was not true, the
conditions of their life previous to the experiments were
known, and were such as would have had no influence in
determining the quality of their reactions in the particular
experiments to which they were subjected. It is not worth
while to recount the means taken so to regulate the chick’s
environment that his experience along certain lines should
be in its entirety known to the observer and that conse-
quently his inherited abilities could be surely differentiated.
The nature of the experiments will, in most cases, be such
that little suspicion of the influence of education by ex-
perience will be possible. In the other cases I will mention
the particular means then taken to prevent such influence.

Some of my first experiments were on color vision in
chicks from 18 to 30 hours old, just old enough to move
about readily and to be hungry. On backgrounds of white
and black cardboard were pasted pieces of colored paper
about 2mm. square. On each background there were six

1 This chapter appeared originally in the Psychological Review, Vol. VI,
No. 3.
156

The Instinctive Reactions of Young Chicks 157

of these pieces, —one each of yellow, red, orange, green,
blue and black (on the white ground) or white (on the black).
They were in a row about half an inch apart. The chicks
had been in darkness for all but three or four hours of their
life so far. During those few hours the incubator had been
illuminated and the chicks had that much chance to learn
color. |

The eight chicks were put, one at a time, on the sheet of
cardboard facing the colored spots. Count was kept of the
number of times that they pecked at each spot and, of
course, they were watched to see whether they would peck
at all at random. In the experiments with the white back-
ground all the colors were reacted to (.e. pecked at) ex-
cept black (but the letters on a newspaper were pecked at by
the same chicks the same day). One of the chicks pecked
at all five, one at four, three at three, one at two and one at
yellow only. These differences are due probably to acci-
dental position or movements. Taking the sums of the re-
actions to each color-spot we get the following table : —

I

Times REACTED TO | ToTaL NUMBER OF Pecks!

| SSG Ss es Seam Sale Bae me 12 31
Yellow . 9 21
Orange . 6 34
Green . 5 II
Blue I 3

I should attach no importance whatever to the quantita-
tive estimate given in the table. The only fact of value so
1This double rating is necessary because of the fact that the chick often

gives several distinct pecks in a single reaction. The ‘times reacted to’
mean the number of different times that the chicks noticed the color.

158 Animal Intelligence

far is the evidence that from the first the chick reacts to all
colors. In no case was there any random pecking at the
white surface of the cardboard.

On a black background the same chicks reacted to all the
colors.

II is a table of the results.

II

Times REACTED TO | TOTAL NUMBER OF PECKS

White 6 19
Blue 4 EI
Red . 4 8
Green 4 4
Orange . 2 7
Yellow . 2 4

In other experiments chicks were tried with green spots on
a red ground, red spots on a green ground, yellow spots on an
orange ground, green spots on a blue ground, and black spots
ona white ground. All were reacted to. Thus, what is ap-
parently a long and arduous task to the child is heredity’s
gift to the chick. It is conceivable, though to me incred-
ible, that what the chick reacts to is not the color, but the
very minute elevation of the spot. My spots were made so
that they were only the thickness of thin paper above paste-
board. Any one who cares to resort to the theory that this
elevation caused the reaction can settle the case by using
color-spots absolutely level with the surface.’

‘The crude experiments reported in this and the preceding paragraphs
were not made to test the presence of color vision proper, that is, of differ-
entiation of two colors of the same brightness, but only to ascertain how
chicks reacted to ordinary colored objects. It was, however, almost certain
from the relative frequency of the reactions that the intensity factor was not

the cause of the response. For example, if it had been, black on white and
yellow on black should have been pecked at oftener.

The Instinctive Reactions of Young Chicks 159

INSTINCTIVE REACTIONS TO DISTANCE, DIRECTION,
SIZE, ETC.

I have purposely chosen this awkward heading rather
than the simple one, Space-Perception, because I do not wish
to imply that there is in the young chick such consciousness
of space-facts as there is in human beings. All that will be
shown here is that he reacts appropriately in the presence of
space-facts, reacts in a fashion which would in the case of a
man go with genuine perception of space.

If one puts a chick on top of a box in sight of his fellows
below, the chick will regulate his conduct by the height of
the box. To be definite, we may take the average chick of
about 95 hours. If the height is less than 10 inches, he will
jump down as soon as you put him up. At 16 inches he will
jump in from 5 seconds to 3 or 4 minutes. At 22 inches he
will still jump down, but after more hesitation. At 274
inches 6 chicks out of eight at this age jumped within 5 min-
utes. At 39 inches the chick will Not ump down. The
numerical values given here would, of course, vary with the
health, development, hunger and degree of lonesomeness of
the chick. All that they are supposed to show is that at any
given age the chick without experience of heights regulates
his conduct rather accurately in accord with the space-fact
of distance which confronts him. The chick does not peck
at objects remote from him, does not, for instance, confuse
a bird a score of feet away with a fly near by, or try to get
the moon inside his bill. Moreover, he reacts in pecking
with considerable accuracy at the very start. Lloyd Mor-
gan has noted that in his very first efforts the chick often
fails to seize the object, though he hits it, and on this ground
has denied the perfection of the instinct. But, as a matter
of fact, the pecking reaction may be as perfect at birth as it is

160 Animal Intelligence

after 10 or 12 days’ experience. It certainly is not perfect
then. I took nine chicks from 10 to 14 days old and placed
them one at a time on a clear surface over which were scat-
tered grains of cracked wheat (the food they had been eat-
ing in this same way for a week) and watched the accuracy
of their pecking. Out of 214 objects pecked at, 159 were
seized, 55 were not. Out of the 159 that were seized, only
116 were seized on the first peck, 25 on the second, 16 on the
third, and the remaining two on the fourth. Of the 55 that
were not successfully seized, 31 were pecked at only once,
10 twice, 10 three times, 3 four times and 1 five times. I
fancy one would find that adult fowls would show by no
means a perfect record. So long as chicks with ten days’
experience fail to seize on the first trial 45 per cent of the
time, it is hardly fair to argue against the perfection of the
instinct on the ground of failures to seize during the first day.

The chick’s practical appreciation of space-facts is seen
further in his attempts to escape when confined. Put chicks
only twenty or thirty hours old in a box with walls three or
four inches high and they will react to the perpendicularity
of the confining walls by trying to jump over them. In fact,
in the ways he moves, the directions he takes and the objects
he reacts to, the chicken has prior to experience the power
of appropriate reaction to colors and facts of all three dimen-
sions.

INSTINCTIVE MuscuLAR COORDINATIONS

In the acts already described we see fitting codrdinations
at work in the chick’s reactions to space-facts. A few more
samples may be given. In jumping down from heights the
chick does not walk off or fall off (save rarely), but jumps
off. He meets the situation “loneliness on a small eminence”
by walking around the edge and peering down; he meets the

The Instinctive Reactions of Young Chicks 161

situation “‘sight of fellow chicks below ” by (after an amount
of hesitation varying roughly with the height) jumping off,
holding his stubby wings out and keeping right side up. He
lands on his feet almost every time and generally very
cleverly. A four days’ chick will jump down a distance
eight times his own height without hurting himself a bit. If
one takes a chick two or three weeks old who has never had
a chance to jump up or down, and puts him in a box with
walls three times the height of the chick’s back, he will
find that the chick will jump, or rather fly, nearly, if not
quite, over the wall, flapping his wings lustily and holding
on to the edge with his neck while he clambers over. Chicks
one day old will, in about 57 per cent of the cases, balance
themselves for five or six seconds when placed on a stiff,
perch. If eight or nine days old, they will, though never
before on any perch or anything like one, balance perfectly
fora minute or more. The muscular codrdination required
is Invoked immediately when the chick feels the situation
“feet on a perch.” The strength is lacking in the first few
days. From the fifth or sixth day on chicks are also able
(their ability increases with age) to balance themselves on a
slowly swinging perch.

Another complex coérdination is seen in the somewhat re-
markable instinct of swimming. Chicks only a day or two
old will, if tossed into a pond, head straight for the shore and
swim rapidly to it. It is impossible to compare their move-
ments in so doing with those of ducklings, for the chick is
agitated, paddles his feet very fast and swims to get out,
not for swimming’s sake. Dr. Bashford Dean, of Colum-
bia University, has suggested to me that the movements
may not be those of swimming, but only of running. At all
events, they are utterly different from those of an adult fowl.
In the case of the adult there is no vigorous instinct to strike

M

162 Animal Intelligence

out toward the shore. The hen may try to fly back into the
boat if it is dropped overboard, and whether dropped in or
slung in from the shore, will float about aimlessly for a while
and only very slowly reach the shore. The movements the
chick makes do look to be such as trying to run in water
might lead to, but it is hard to see why a hen shouldn’t run
to get out of cold water as well as a chick. If, on the other
hand, the actions of the chick are due to a real swimming in-
stinct, it is easy to see that, being unused, the instinct might
wane as the animal grew up.

Such instinctive codrdinations as these, together with the
walking, running, preening of feathers, stretching out of leg
backward, scratching the head, etc., noted by other obser-
vers, make the infant chick a very interesting contrast to the
infant man. That the helplessness of the child is a sacrifice
to plasticity, instability and consequent power to develop we
all know; but one begins to realize how much of a sacrifice
when one sees what twenty-one days of embryonic life do for
the chick brain. And one cannot help wondering whether
some of the space-perception we trace to experience, some
of the co6érdinations which we attribute to a gradual devel-
opment from random, accidentally caused movements may
not be more or less definitely provided for by the child’s
inherited brain structure. Walking has been found to be
instinctive; why not other things ?

INSTINCTIVE EMOTIONAL REACTIONS

The only experiments to which I wish to refer at length
under this heading are some concerning the chick’s instinc-
tive fears. Before describing them, it may be well to men-
tion their general bearing on the results obtained by Spald-
ing and Morgan. They corroborate Morgan’s decision that
no well-defined specific fears are present; that the fears of

The Instinctive Reactions of Young Chicks 163

young chicks are of strange moving objects in general, shock
in general, strange sounds in general. On the other hand, no
such general disturbances of the chick’s environment led to
such well-marked reactions as Spalding described. And so
when Morgan thinks that such behavior as Spalding wit-
nessed on the part of the chick that heard the hawk’s cry
demands for its explanation nothing more than a general
fear of strange sounds, my experiments do not allow me to
agree with him. If Spalding really saw the conduct which
he says the chick exhibited on the third day of its life in the
presence of man, and later at the stimulus of the sight or
sound of the hawk, there are specific reactions. For the
running, crouching, silence, quivering, etc., that one gets
by yelling, banging doors, tormenting a violin, throwing
hats, bottles, or brushes at the chick is never anything like so
pronounced and never lasts one tenth as long as it did with
Spalding’s chicks. But, as to the fear of man, Spalding
must have been deluded. In the second, third and fourth
days there is no such reaction to the sight of man as he
thought he saw. Miss Hattie E. Hunt, in the American
Journal of Psychology, Vol. 1X., No. 1, asserts that there is
no instinctive fear of a cat. Morgan did not find such. I
myself put chicks of 2, 5, 9 and 17 days (different individ-
uals each time, 11 in all) in the presence of a cat. They
showed no fear, but went on eating as if there was nothing
about. The cat was still, or only slowly moving. I further
put a young kitten (eight inches long) in the pen with
chicks. He felt of them with his paw, and walked around
among them for five or ten minutes, yet they showed no fear
(nor did he instinctively attack them). If, however, you let
a cat jump at chicks in real earnest, they will not stay to be
eaten, but will manifest fear — at least chicks three to four
weeks old will. I did not try this experiment with chicks

164 Animal Intelligence

at different ages, because it seemed rather cruel and degrad-
ing to the experimenter. When in the case of the older chicks
nature happened to make the experiment, it was hard to de-
cide whether there was more violent fear of the jumping cat
than there was when one threw a basket or football into the
pen. There was not very much more.

We may now proceed to a brief recital of the facts shown
by the experiments in so far as they are novel. It should be
remembered throughout that in every case chicks of differ-
ent ages were tested so as to demonstrate transitory in-
stincts if such existed, e.g., the presence of a fear of flame
was tested with chicks 59 and 60, one day old, 30 and 32, two
days old, 21 and 22, three days old, 23 and 24, seven days
old, 27 and 29, nine days old, 16 and 19, eleven days old,
and so on up to twenty-days-old chicks. By thus using
different subjects at each trial one, of course, eliminates any
influence of experience.

The first notable fact is that there develops in the first
month a general fear of novel objects in motion. For four
or five days there seems to be no such. You may throw a
hat or slipper or shaving mug at a chick of that age, and he
will do no more than get out of the way of it. But a twenty-
five-days-old chick will generally chirr, run and crouch for
five or ten seconds. My records show this sort of thing be-
ginning about the tenth day, but it is about ten days more
before it is very marked. In general, also, the reaction is
more pronounced if many chicks are together, and is then
displayed earlier (only two at a time were taken in the ex-
periments the results of which have just been quoted).
Thus the reaction is to some degree a social performance, the
presence of other chicks combining with the strange object
to increase the vigor of the reaction. Chicks ordinarily
scatter apart when they thus run from an object.

The Instinctive Reactions of Young Chicks 165

One witnesses a similar gradual growth of the fear of man
(not as such probably, but merely as a large moving object).
For four or five days you can jump at the chick, grab at it
with your hands, etc., without disturbing it in the least. A
chick twenty days old, however, although he has never been
touched or approached by a man, and in some cases never
seen one except as the daily bringer of food, and has never
been in any way injured by any large moving object of any
sort, will run from you if you try to catch him or even get
very near him. There is, however, even then, nothing like
the utter fear described by Spalding.

Up to thirty days there was no fear of a mocking bird into
whose cage the chicks were put, no fear of a stuffed hawk ora
stuffed owl (kept stationary). Chicks try to escape from
water (even though warmed to the temperature of their
bodies) from the very first. Up to forty days there appears
no marked waning of the instinct. They did not show any
emotional reaction to the flame produced by six candles
stuck closely together. From the start they react instinc-
tively to confinement, to loneliness, to bodily restraint, but
their feeling in these cases would better be called discomfort
than fear. From the roth or 12th to the 2oth day, and
probably later and very possibly earlier, one notices in
chicks a general avoidance of open places. Turn them out
in your study and they will not go out into the middle of the
room, but will cling to the edges, go under chairs, around
table legs and along the walls. One sees nothing of the sort
up through the fourth day. Some experiments with feed-
ing hive bees to the chicks are interesting in connection with
the following statement by Lloyd Morgan: ‘One of my
chicks, three or four days old, snapped up a hive bee and
ran off with it. Then he dropped it, shook his head much
and often, and wiped his bill repeatedly. I do not think

166 Animal Intelligence

he had been stung: probably he tasted the poison” (‘Intro-
duction to Comparative Psychology,’ p. 86). I fed seven
bees apiece to three chicks from ten to twenty days old.
They ate them all greedily, first smashing them down on the
ground violently ina rather dexterous manner. Apparently
this method of treatment is peculiar to the object. Chicks
three days old did not eat the bees. Some pecked at
them, but none would snap them up, and when the bee
approached, they sometimes sounded the danger note.

Finally an account may be given of the reaction of chicks
at different ages, up to twenty-six days, to loud sounds.
These were the sounds made by clapping the hands, slam-
ming a door, whistling sharply, banging a tin pan on the
floor, mewing like a cat, playing a violin, thumping a coal
scuttle with a shovel, etc. Two chicks were together in
each experiment. Three fourths of the times no effect
was produced. On the other occasions there was some run-
ning or crouching or, at least, starting to run or crouch;
but, as was said, nothing like what Spalding reports as the
reaction to the ‘cheep’ of the hawk. It is interesting to
notice that the two most emphatic reactions were to the
imitation mew. One time a chick ran wildly, chirring, and
then crouched and stayed still until [had counted 105. The
other time a chick crouched and stayed still until I counted
40. But the other chick with them did not; and in adozen
other cases the ‘meaw’ had no effect.

I think that the main interest of most of these experiments
is the proof they afford that instinctive reactions are not
necessarily definite, perfectly appropriate and unvarying re-
sponses to accurately sensed and, so to speak, estimated
stimuli. The old notion that instinct was a God-given sub-
stitute for reason left us an unhappy legacy in the shape
of the tendency to think of all inherited powers of reaction as

The Instinctive Reactions of Young Chicks 167

definite particular acts invariably done in the presence of
certain equally definite situations. Such an act as the
spider’s web-spinning might be a stock example. Of
course, there are many such instinctive reactions in which a
well-defined act follows a well-defined stimulus with the
regularity and precision with which the needle approaches
the magnet. But our experiments show that there are acts
just as truly instinctive, depending in just the same way on
inherited brain-structure, but characterized by being vague,
irregular, and to some extent dissimilar, reactions to vague,
complex situations.

The same stimulus doesn’t always produce just the same
effect, doesn’t produce precisely the same effect in all in-
dividuals. The chick’s brain is evidently prepared in a
general way to react more or less appropriately to certain
stimuli, and these reactions are among the most important
of its instincts or inherited functions. But yet one cannot
take these and find them always and everywhere. This
helps us further to realize the danger of supposing that in
observation of animals you can depend on a rigid uniform-
ity. One would never suppose because one boy twirled
his thumb when asked a question that all boys of that age
did. But naturalists have been ready to believe that
because one young animal made a certain response to a cer-
tain stimulus, the thing was an instinct common to all in pre-
cisely that same form. But a loud sound may make one
chick run, another crouch, another give the danger call, and
another do nothing whatever.

In closing this article I may speak of one instinct which
shows itself clearly from at least as early as the sixth day,
which is preparatory to the duties of adult life and of no
other use whatsoever. It is interesting in connection with
the general matter of animal play. The phenomenon is as

168 Animal Intelligence

follows: The chicks are feeding quietly when suddenly two
chicks rush at each other, face each other a moment and then
go about their business. This thing keeps up and grows
into the ordinary combat of roosters. It is rather a puzzle
on any theory that an instinct needed so late should begin
to develop so early.

CHAPTER. TV

A NoTE ON THE PsycHoLoGy oF FisuHEs!

NvuMEROUs facts witness in a vague way to the ability of
fishes to profit by experience and fit their behavior to situa-
tions unprovided for by their innate nervous equipment.
All the phenomena shown by fishes as a result of taming are,
of course, of this sort. But such facts have not been exact
enough to make clear the mental or nervous processes in-
volved in such behavior, or simple enough to be available as
demonstrations of such processes. It seemed desirable to
obtain evidence which should demonstrate both the fact and
the process of learning or intelligent activity in the case of
fishes and demonstrate them so readily that any student
could possess the evidence first hand.

Through the kindness of the officials of the United States
Fish Commission at Woods Holl, especially of the director,
Dr. Bumpus, I was able to test the efficiency of some simple
experiments directed toward this end. The common Fun-
dulus was chosen as a convenient subject, and also because
of the neurological interest attaching to the formation of
intelligent habits by a vertebrate whose forebrain lacks a
cortex.

The fishes studied were kept in an aquarium (about 4 feet
long by 2 feet wide, with a water depth of about 9 inches)
represented by Fig. 24. The space at one end, as repre-

1 This chapter appeared originally in the American Naturalist, Vol. XX XIII,
No. 306.

169

170 Animal Intelligence

sented by the lines in the figure, was shaded from the sun by
a cover, and all food was get: inatthisend. Along each
side of the aquarium were
| fastened simple pairs of
cleats, allowing the ex-
perimenter to put across
it partitions of wood,
¢ glass or wire screening.
I 7 One of these in position
wae is shown in the figure by
the dotted line. These partitions were made each with an
opening, as shown in Fig. 25. If now we cause the fish to
leave his shady corner and swim up to

the sunny end by putting a slide (with-
out any opening) in behind him atD ]|

and moving it gently from D to A and

then place, say slide 7, across the
aquarium at 1, we shall have a chance I

to observe the animal’s behavior to

good purpose. :

This fish dislikes the sunlight and
tries to get back to D. He reactsto WL
the situation in which he finds himself BGO Ay:
by swimming against the screen, bumping against it here
and there along the bottom. He may stop and remain
still for a while. He will occasionally rise up toward the
top of the water, especially while swimming up and down
the length of the screen. When he happens to rise up to the
top at the right-hand end, he has a clear path in front of him
and swims to D and feels more comfortable.

If, after he has enjoyed the shade fifteen minutes or more,
you again confine him in A, and keep on doing so six or eight
times a day for a day or so, you will find that he swims

’
'
'
1
1
'
'
'
'

A Note on the Psychology of Fishes 171

against the screen less and less, swims up and down along it
fewer and fewer times, stays still less and less, until finally
his only act is to go to the right-hand side, rise up, and
swim out. In correspondence with this change in behavior
you will find a very marked decrease in the time he takes to
escape. The fish has clearly profited by his experience and
modified his conduct to suit a situation for which his innate
nervous equipment did not definitely provide. He has, in
common language, learned to get out.

This particular experiment was repeated with a number of
individuals. Another experiment was made, using three
slides, JJ, IIT, and another, requiring the fish to find his way
from A to B, BtoC, and from C to D. The results of these
and still others show exactly the same general mental
process as does the one described — a process which I have
discussed at length elsewhere.

Whatever interest there is in the demonstration in the case
of the bony fishes of the same process which accounts for so
much of the behavior of the higher vertebrates may be left to
the neurologists. The value of the experiment, if any, to
most students will perhaps be the extreme simplicity of the
method, the ease of administering it, and its possibilities.
By using long aquaria, one can study the formation of very
complex series of acts and see to what extent any fish can
carry the formation of such series. By proper arrange-
ments the delicacy of discrimination of the fish in any re-
spect may be tested. The artificiality of the surroundings
may, of course, be avoided when desirable.

CHAPTER V

Tae MENTAL LIFE oF THE MONKEYS; AN EXPERIMENTAL
Stupy !

Tue literary form of this monograph is not at all satis-
factory to its author. Compelled by practical considera-
tions to present the facts in a limited space, he has found it
necessary to omit explanation, illustration and many rhetor-
ical aids to clearness and emphasis. For the same reason
detailed accounts of the administration of the experiments
have not always been given. In many places theoretical
matters are discussed with a curtness that savors of dog-
matism. In general when a theoretical point has appeared
justified by the evidence given, I have, to economize space,
withheld further evidence.

There is, however, to some extent a real fitness in the lack
of clearness, completeness and finish in the monograph. For
the behavior of the monkeys, by virtue of their inconstant
attention, decided variability of performance, and generally
aimless, unforetellable conduct would be falsely represented
in any clean-cut, unambiguous, emphatic exposition. The
most striking testimony to the mental advance of the mon-
keys over the dogs and cats is given by the difficulty of mak-
ing clear emphatic statements about them.

1 This chapter appeared originally as Monograph Supplement No. 15 to
the Psychological Review.

172

The Mental Life of the Monkeys £73

INTRODUCTION

The vvork to be described in this paper is a direct contin-
uation of the work done by the author in 1897-1898 and
described in Monograph Supplement No. 8 of the Psycho-
logical Review under the heading, ‘Animal Intelligence ;
an Experimental Study of the Associative Processes in
Animals.’! This monograph affords by far the best in-
troduction to the present discussion, and I shall therefore
assume an acquaintance with it on the part of my readers.

It will be remembered that evidence was there given that
ordinary mammals, barring the primates, did not infer or
compare, did not imitate in the sense of ‘learning to do an
act from seeing it done,’ did not learn various simple acts
from being put through them, showed no signs of having in
connection with the bulk of their performances any mental
images. Their method of learning seemed to be the grad-
ual selection of certain acts in certain situations by reason
of the satisfaction they brought. Quantitative estimates
of this gradualness were given for a number of dogs and
cats. Nothing has appeared since the ‘Experimental Study’
to negate any of these conclusions in the author’s mind.
The work of Kline and Small? on rodents shows the same
general aspect of mammalian mentality.

Adult human beings who are not notably deficient in
mental functions, at least all such as psychologists have
observed, possess a large stock of images and memories.
The sight of a chair, for example, may call up in their minds
a picture of the person who usually sits in it, or the sound
of his name. The sound of a bell may call up the idea of

1 Pp. 20 to 155 of this volume.

2 American Journal of Psychology, Vol. X, pp. 256-279; Vol. XI, pp. 80-
100, 131-165; Vol. XII, pp. 206-239.

174 Animal Intelligence

dinner. The outside world also is to them in large part a
multitude of definite percepts. They feel the envirsnment
as trees, sticks, stones, chairs, tables, letters, words, etc.
I have called such definite presentations ‘free ideas’ to
distinguish them from the vague presentations such as
atmospheric pressure, the feeling of malaise, of the position
of one’s body when falling, etc. It is such ‘free ideas’
which compose the substance of thought and which
lead us to perhaps the majority of the different acts we
perform, though we do, of course, react to the vaguer sort
as well. I saw definitely in writing the last sentence the
words ‘majority of the different acts’ and thought ‘we
perform’ and so wrote it. I see a bill and so take check
book and pen and write. I think of the cold outside and
so put on an overcoat. This mental function ‘having free
ideas,’ gives the possibility of learning to meet situations
properly by thinking about them, by being reminded of
some property of the fact before us or some element therein.

We can divide all learning into (1) learning by trial and
accidental success, by the strengthening of the connections
between the sense-impressions representing the situation
and the acts—or impulses and acts — representing our
successful response to it and by the inhibition of similar
connections with unsuccessful responses; (2) learning by
imitation, where the mere performance by another of a
certain act in a certain situation leads us to do the same;
and (3) learning by ideas, where the situation calls up some
idea (or ideas) which then arouses the act or in some way
modifies it.

The last method of learning has obviously been the means
of practically all the advances in civilization. The evidence
quoted a paragraph or so back from the Experimental
Study shows the typical mammalian mind to be one which

The Mental Life of the Monkeys 775

rarely or never learns in this fashion. The present study
of the primates has been a comparative study with two
main questions in view: (1) How do the monkeys vary
from the other mammals in the general mental functions
revealed by their methods of learning? (2) How do they,
on the other hand, vary from adult civilized human beings ?

The experiments to be described seem, however, to be of
value apart from the possibility of settling crucial questions
by means of the evidence they give. To obtain exact
accounts of what animals can learn by their own unaided
efforts, by the example of their fellows or by the tuition
of a trainer, and of how and how fast they learn in each
case, seems highly desirable. I shall present the results
in the manner which fits their consideration as arguments
for or against some general hypotheses, but the naturalist
or psychologist lacking the genetic interest may find an
interest in them at their face value. I shall confine myself
mainly to questions concerning the method of learning of
the primates, and will discuss their sense-powers and un-
learned reactions or instincts only in so far as is necessary
to its comprehension.

It has been impossible for the author to make helpful
use of the anecdotes and observations of naturalists and
miscellaneous writers concerning monkey intelligence.
The objections to such data pointed out in Chapter I,
pp. 22-26, hold here. Moreover it is not practicable
to sift out the true from the false or to interpret'these
random instances of animal behavior even if assuredly true.
In the study of animal life the part is only clear in the
light of the whole, and it is wiser to limit conclusions to
such as are drawn from the constant and systematic study
of a number of animals during a fairly long time. After
a large enough body of such evidence has been accumulated
we may be able to interpret random observations.

176 Animal Intelligence

The subjects of the experiments were three South Ameri-
can monkeys of the genus Cebus. At the time of beginning
the experiment No. 1 was about half grown, No. 2 was about
one fourth full size and No. 3 was about half grown. No.1
was under observation from November, 1899, to February,
1900; No. 2 and No. 3 from October, 1g00, to February,
tgo1. No. 1 was during the period of experimentation
decidedly tame, showing no fear whatever of my presence
and little fear at being handled. He would handle and
climb over me with no hesitation. No. 2 was timid, did
not allow handling, but showed no fear of my presence and
no phenomena that would differentiate his behavior in
the experiments discussed from that of No. 1, save much
greater caution in all respects. No. 3 also showed no fear
at my presence. Any special individual traits that are of
importance in connection with any of the observations will
be mentioned in their proper places. No. 1 was kept until
June, 1900, in my study in a cage 3 by 6 by 6 feet, and was
left in the country till October, 1900. From October, 1900,
all three were kept in a room 8 by g feet, in cages 6 feet tall
by 3 long by 2.6 wide for Nos. 1 and 2, 3 feet by 3 feet by 20
inches for No. 3. I studied their behavior in learning to
get into boxes, the doors to which could be opened by
operating some mechanical contrivance, in learning to
obtain food by other simple acts, in learning to discriminate
between two signals, that is, to respond to each by a dif-
ferent act, and in their general life.

Following the order of the ‘Animal Intelligence,’ I shall
first recount the observations of the way the monkeys
learned, solely by their own unaided efforts, to operate
simple mechanical contrivances.

Besides a number of boxes such as were used with the
dogs and cats (see illustration on p. 30), I tried a variety

The Mental Life of the Monkeys 177

of arrangements which could be set up beside a cage, and
which would, when some simple mechanism was set in
action, throw a bit of food into the cage. Figure 26
shows one of these. See description of QQ (ff) on page 182.

$3...

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Fic. 26. A, loop; BB, lever, pivoted at M. A bit of food put in front of C
would be thrown down the chute DDD when A was released.

APPARATUS

The different mechanisms which I used were the follow-
ing : —

Box BB (O at back) was about 20 by 14 by 12 inches with
a door in the front which was held by a bolt to which was
tied a string. This string ran up the front of the box out-
side, over a pulley, across the top, and over another pulley
down into the box, where it ended in a loop of wire.

Box MM (bolt) was the same as BB but with no string
and loop attachment to the bolt.

Box CC (single bar) was a box of the same size as BB,
N

178 Animal Intelligence

The door was held by a bar about 3 by 1 by 5 inches which
swung on a nail at the left side.

Box CCC (double bar) was CC with a second similar
bar on the right side of the door.

Box NN (hook) was a box about the size of BB with its
door held by an ordinary hook on the left side which hooked
through an eyelet screwed into the door.

Box NNN was NN with the hook on the right instead
of the left side.

Box NNNN was box NN with two hooks, one on each
side.

Apparatus OO (string box) consisted of a square box tied
to a string, which formed a loop running over a pulley by
the cage and a pulley outside, so that pulling on the under
string would bring the box to the cage. In each experiment
the box was first pulled back to a distance of 2 feet 3 inches
from the cage, and a piece of banana putin it. The mon-
key could, of course, secure the banana by pulling the box
near enough.

Apparatus OOO was the same as OO, with the box tied
to the upper string, so that the upper string had to be pulled
instead of the lower.

Box PP was about the size of BB. Its door was held by
a large string securely fastened at the right, passing across
the front of the door and ending in a loop which was put
over a nail on the box at the left of the door. By pulling
the string off the nail the door could be opened.

Box RR (wood plug) was a box about the size of BB.
The door was held by a string at its top, which passed up
over the front and top to the rear, where it was fastened
to a wooden plug which was inserted in a hole in the top of
the box. When the plug was pulled out of the hole, the
door would fall open.

The Mental Life of the Monkeys 179

Box SS (triple; wood-plug, hook and bar) was a box
about the size of BB. To open the door, a bar had to be
pushed around, a hook unhooked and a plug removed from
a hole in the top of the box.

Box TT (nail plug) was 14 by 10 by 10 inches with a door
5.5 by 10 on the right side of the front, the rest of the front
being barred up. The door was hinged at the bottom and
fastened at its top to a wire which was fastened to a nail
2.5 inches long, which, when inserted in a hole 0.25 inches
in diameter at the back of the top of the box, held the door
closed. By drawing out this nail and pulling the door
the animal could open the door.

Box VV (plug at side) was a box about 18 by to by to,
the door held by a plug passing through a hole in the side
of the box. When the plug was pulled out, the door could
be pushed inward.

Box W (loop) was 17 by 10 by to inches with a door 5 by 9
at the left side of its front hinged at the bottom. The door
was prevented from falling inward by a wire stretched
behind it. It was prevented from falling outward by a
wire firmly fastened at the right side and held by a loop over
a nail at the left. By pulling the loop outward and to the
left it could be freed from the nail. The door could then
be pulled open.

Box WW (bar inside) was 16 by 14 by 10 inches with a
door 4 by 11 at the left of its front hinged at the bottom.
The door could be pushed in or pulled out when a bar on
its inside was lifted out of a latch. The bar was accessible
from the outside through an opening in the front of the
box. It had to be lifted to a height of 1.5 inches (an angle
of about 30°).

Box XX (bar outside) was about 13 by 11 by ro inches
with a door 7 by 8 on the left side of the front. The door

180 Animal Intelligence

was held in place by a bar swinging on a nail at the top,
with its other end resting in a latch at the left side of the
box. By pushing this up through an angle of 45° the door
could be opened.

Box YY (push bar) was a box 16 by 8 by 12 inches with
a door at the left of its front. The door was held by a brass
bar which swung down in front of an L-shaped piece of
steel fastened to the inside of the door. This brass bar
was hung on a pivot at its center and the other end at-
tached to a bar of wood; the other end of this bar projected
through a hole at the right side of the box. By pushing
this bar in about an inch the door could be opened.

Box LL (triple; nail plug, hook and bar) was a box 10 by
10 by 13 with a door 3 by 8.5 at the left side. The door
could be opened only after (1) a nail plug had been removed
from a hole in the back of the top of the box as in TT, (2) a
hook in the door had been unhooked, and (3) a bar on the
left side had been turned from a horizontal to a vertical
position.

Box Alpha (catch at back) was 11 by 10 by 15 with the
door (4 by 4) in the left side of its front. The door was held
by a bolt, which, when let down, held in a catchon the inside
of the door. A string fastened to the bolt ran across to
the back of the box and through a hole to the outside.
There it ended in a piece of wood 2.5 by 1 by .25 inches.
When this piece of wood was pulled, the bolt went up and
the door fell open.

Box Beta was the same as NN except in size. It was
10 by 10 by 13 inches.

Box KK (triple; bolt, side plug, and knob) was a box 16
by 9 by 11 with a door at the left side of the front. The
door was held by a bolt on the right side, a wooden plug
stuck through a hole in the box on its left side and a nail

The Mental Life of the Monkeys 181

which held in a catch at its top. This nail was fastened
to a wooden knob (1 by 5 by .375) which lay in a depression
at the top of the box. Only when the bolt had been
drawn and the plug and knob pulled, could the door be
opened.

Box Gamma (wind) was 10 by 10 by 13 inches with its
door held by a wire fastened at the top and wound three
times about a screw eye in the top of the box. By unwind-
ing the wire the door could be opened.

Box Delta (push back) was 12 by 11 by 10 inches. Its
door was held by a wooden bar projecting from the right
two inches in front of it. This bar was so arranged that
it could be pushed or pulled toward the right, allowing the
door to fall open. It could not be swung up or down.

Box Epsilon (lever or push down) was 12 by g by 5 inches.
At the right side of its front was a hole 4 inch broad by 14
inches up and down. Across this hole on the inside of the
box was a strip of brass, the end of one bar of a lever. If
this strip was depressed $ of an inch, the door at the extreme
left would be opened by a spring.

Box Zeta (side plug) was 12 by 11 by ro inches. Its door
was held by a round bar of wood put through a hoop of
steel at the left side of the box. This bar was loose and
could easily be pulled out, allowing the door to be opened.

Box Theta was the same as KK except that the door
could be opened as soon as the bolt alone was pulled or
pushed up.

Box Eta was like Alpha save that the object at the back
of the box to be pulled was a brass ring.

Apparatus QQ (chute) consisted of a lever mechanism so
arranged that by pushing in a bar of wood { to $n inch,
a piece of banana would be thrown down a chute into the
cage. The apparatus was placed outside the cage in such a

182 Animal Intelligence

way that it could be easily reached by the monkey’s arm
through the wire netting.

QQ (a) was of the same general plan. By turning a
handle through 270° food could be obtained.

QQ (b) was like QQ (a) except that 24 full revolutions
of the handle in one direction were necessary to cause the
food to drop down.

QQ (c) was a chute apparatus so arranged as to work when
a nail was pulled out of a hole.

QQ (d) was arranged to work at a sharp pull upon a brass
ring hanging to it.

QQ (e) was arranged to work when a hook was unhooked.

QQ (f) was arranged to work when a loop at the end of a
string was pulled off from a nail.

QQ (ff) was QQ (f) with a stiff wire loop instead of a loop
of string.

EXPERIMENTS ON THE ABILITIES OF THE MONKEYS
TO LEARN WITHOUT TUITION

I will describe a few of the experiments with No. 1 as
samples and then present the rest in the form of a table.
No. 1 was tried first in BB (O at back) on January 17, 1900,
being put inside. He opened the box by pulling up the
string just above the bolt. His times were .05, 1.38, 6.00,
I.00, .10, .05, .05. He was not easily handled at this time,
so I changed the experiment to the form adopted in future
experiments. I put the food inside and left the animal to
open the door from the outside. He pulled the string up
within ro seconds each time out of 10 trials.

I then tried him in MM (bolt). He failedin 15. I then
(January 18th) tried him in CC (single bar outside.) He
got in in 36.00 minutes; he did not succeed a second time

The Mental Life of the Monkeys 183

that night, but in the morning the box was open. His
times thenceforth were 20, 10, 16, 25 and on January roth,
RO; 5,12, 8; 5375, 5 Seconds.

I then tried him (January 21, 1900) in CCC ( double bar).
He did it at first by pushing the old bar and then pulling
at the door until he worked the second bar gradually
around. Later he at times pushed the second bar. The
times taken are shown in the time-curve. I then (Janu-
ary 25th) tried him in NN (hook). See time-curves on
page 185. I then (January 27th) tried him in NNN (hook
on other side). He opened it in 6, 12 and 4 seconds in the
first three trials. I then (20 minutes later) tried him with
NNNN (double hook). He opened the door in 12, 10, 6
and 6 seconds. I then (January 27th) tried him with PP
(string across). He failed in ro. I then (February a2tst)
tried him with apparatus OO (string box). For his progress
as shown by the times taken see the time-curve. His
progress is also shown in the decrease of the useless pullings
at the wrong string. There were none in the gth trial,
14th, 15th, 16th, 18th, 24th, and following trials.

No. 1 was then (February 24th) tried with OOO (string
box with box on upper string). No. 1 succeeded in 2.20,
then failed in 10.00. The rest of the experiment will be
described under imitation.

He was next tried (March 24th) with apparatus QQ
(chute). He failed in 10.00, though he played with the ap-
paratus much of the time. Other experiments were with
box RR (wood-plug) (April 5th). He failed in 10.00.
After he had, in a manner to be described later, come to
succeed with RR, he was tried in box SS (triple; wood-plug,
hook and bar) (April 18th); see time-curve. No more
experiments of this nature were tried until October, 1900.

The rest of the experiments with No. 1 and all those with

184 Animal Intelligence

No. 2 and No. 3 may best be enumerated in the form of a
table. (See Table 9 on page 187.) It will show briefly the
range of performances which the unaided efforts of the
animals can cope with. It will also give the order in which
each animal experienced them. F means that the animal
failed to succeed. The figures are minutes and seconds,
and represent the time taken in the first trial or the
total time taken without success where there isan F. In
cases where the animal failed in say 10 minutes, but in a
later trial succeeded, say in 2.40, the record will be 2.40
after 10 F. There are separate columns for all three ani-
mals, headed No. 1, No. 2 and No. 3. Im. stands for a prac-
tically immediate success.

The curves on pages 185 and 186 (Figs. 27 and 28) show the
progress of the formation of the associations in those cases
where the animal was given repeated trials, with, however,
nothing to guide him but his own unaided efforts. Each
millimeter on the abscissa represents one trial and each
millimeter on the ordinate represents ro seconds, the ordi-
nates representing the time taken by the animal to open
the box. A break in the curve, or an absence of the curve
at the beginning of the base-line represents cases where the
animal failed in 10 minutes or took a very long time to get
out.

In discussing these facts we may first of all clear our way
of one popular explanation, that this learning was due to
‘reasoning.’ If we use the word reasoning in its technical
psychological meaning as the function of reaching conclu-
sions by the perception of relations, comparison and infer-
ence, if we think of the mental content involved as feelings
of relation, perceptions of similarity, general and abstract
notions and judgments, we find no evidence of reasoning

The Mental Life of the Monkeys 185

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186 Animal Intelligence

in the behavior of the monkeys toward the mechanisms
used. And this fact nullifies the arguments for reasoning in
their case as it did in the case of the dogs and cats. The
argument that successful dealings with mechanical contriv-
ances imply that the animals reasoned out the properties

gra

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of the mechanisms, is destroyed when we find mere selection
from their general instinctive activities sufficient to cause
success with bars, hooks, loops, etc. There is also in the
case of the monkeys, asin that of the other mammals, posi-
tive evidence of the absence of any general function of reason-
ing. We shall find that at least very many simple acts were
not learned by the monkeys in spite of their having seen me
perform them again and again; that the same holds true
of many simple acts which they saw other monkeys do,
or were put through by me. We shall find that after having

187

The Mental Life of the Monkeys

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188 Animal Intelligence

abundant opportunity to realize that one signal meant
food at the bottom of the cage and another none, a monkey
would not act from the obvious inference and consistently
stay up or go down as the case might be, but would make
errors such as would be natural if he acted under the growing
influence of an association between sense-impression and
impulse or sense-impression and idea, but quite incompre-
hensible if he had compared the two signals and made a
definite inference. We shall find that, after experience
with several pairs of signals, the monkeys yet failed, when
a new pair was used, to do the obvious thing to a rational
mind; viz., to compare the two, think which meant food,
and act on the knowledge directly.

The methods one has to take to get them to do anything,
their general conduct in becoming tame and in the ex-
periments throughout, confirm these conclusions. The
following particular phenomena are samples of the many
which are inconsistent with the presence of reasoning as
a general function. No. 1 had learned to open a door by
pushing a bar around from a horizontal to a vertical posi-
tion. The same box was then fitted with two bars. He
turned the first bar round thirteen times before attempting
to push the other bar around. In box LL all three monkeys
would in the early trials do one or two of the acts over and
over after they had once done them. No. 1, who had
learned to pull a loop of wire off from a nail, failed thereafter
to pull off a similar loop made of string. No. 1 and No. 3
had learned to poke their left hands through the cage for
me to take and operate a chute with. It was extremely
difficult to get either of them to put his right hand through
or even to let me take it and pull it through.

A negative answer to the question ‘‘Do the monkeys
reason ?”’ thus seems inevitable, but I do not attach to

The Mental Life of the Monkeys 189

the question an importance commensurate with the part
it has played historically in animal psychology. For I
think it can be shown, and I hope in a later monograph
to show, that reasoning is probably but one secondary
result of the general function of having free ideas in great
numbers, one product of a type of brain which works in
great detail; not in gross associations. The denial of reason-
ing need not mean, and does not to my mind, any denial
of continuity between animal and human mentality or any
denial that the monkeys are mentally nearer relatives to
man than are the other mammals.

So much for supererogatory explanation. Let us now
turn to a more definite and fruitful treatment of these
records.

The difference between these records and those of the
chicks, cats and dogs given on pages 39-65 passim is un-
deniable. Whereas the latter were practically unani-
mous, save in the cases of the very easiest performances,
in showing a process of gradual learning by a gradual
elimination of unsuccessful movements, and a gradual
reénforcement of the successful one, these are unanimous,
save in the very hardest, in showing a process of sudden
acquisition by a rapid, often apparently instantaneous,
abandonment of the unsuccessful movements and a selection
of the appropriate one which rivals in suddenness the
selections made by human beings in similar performances.
It is natural to infer that the monkeys who suddenly re-
place much general pulling and clawing by a single definite
pull at a hook or bar have an idea of the hook or bar and
of the movement they make. The rate of their progress
is so different from that of the cats and dogs that we cannot
help imagining as the cause of it a totally different mental
function, namely, free ideas instead of vague sense-impres-

190 Animal Intelligence

sions and impulses. But our interpretation of these results
should not be too hasty. We must first consider several
other possible explanations of the rapidity of learning
by the monkeys before jumping to the conclusion that the
forces which bring about the sudden formation of associa-
tions in human beings are present.

First of all it might be that the difference was due to the
superiority of the monkeys in clear detailed vision. It
might be that in given situations where associations were
to be formed on the basis of smells, the cats and dogs
would show similar rapid learning. There might be, that is,
no general difference in type of mental functioning, but
only a special difference in the field in which the function
worked. ‘This question can be answered by an investigation
of the process of forming associations in connection with
smells by dogs and cats. Such an investigation will, I
hope, soon be carried on in the Columbia Laboratory by
Mr. Davis.!

Secondly, it might be that the superior mobility and more
detailed and definite movements of the monkeys’ hands
might have caused the difference. The slowness in the
case of the dogs and cats might be at least in part the result
of difficulty in executing movements, not in intending them.
This difficulty in execution is a matter that cannot be readily
estimated, but the movements made by the cats and dogs
would not on their face value seem to be hard. They were
mostly common to the animals’ ordinary life. At the same
time there were certain movements (e.g. depressing the
lever) which were much more quickly associated with their
respective situations by the cats than others were, and if
we could suppose that all the movements learned by the
monkeys were comparable to these few, it would detract

1 This, I regret, was not done [E. L. T., ror].

The Mental Life of the Monkeys IQI

from the necessity of seeking some general mental differ-
ence as the explanation of the difference in the results.

In the third place it may be said by some that no com-
parison of the monkeys with dogs and cats is valid, since
the former animals got out of boxes while the latter got in.
It may be supposed that the instinctive response to confine-
ment includes an agitation which precludes anything save
vague unregulated behavior. Professor Wesley Mills has
made such a suggestion in referring to the ‘Animal Intelli-
gence’ in the Psychological Review, May, 1899. In the
July number of the same journal I tried to show that
there was no solid evidence of such a harmful agitation.
Nor can we be at all sure that agitation when present does _
not rather quicken the wits of animals. It often seems to.
However I should, of course, allow that for purposes of
comparison it would be better to have the circumstances
identical. And I should welcome any antagonist who should,
by making experiments with kittens after the fashion of
these with the monkeys, show that they did learn as sud-
denly as the latter.

Again we know that, whereas the times taken by a cat
in a box to get out are inversely proportional to the strength
of the association, inasmuch as they represent fairly the
amount of its efforts, on the other hand, the times taken by a
monkey to get in represent the amounts of his efforts plus
the amount of time in which he is not trying to getin. It may
be said therefore that the time records of the monkeys prove
nothing, — that a record of four minutes may mean thirty
seconds of effort and three minutes thirty seconds of sleep, —
that one minute may really represent twice as much effort.
As a matter of fact this objection would occasionally hold
against some single record. The earliest times and the
occasional long times amongst very short ones are likely

192 Animal Intelligence

to be too long. The first fact makes the curves have too
great a drop at the start, making them seem cases of too
sudden learning, but the second fact makes the learning
seem indefinite when it really is not. And in the long run
the times taken do represent fairly well the amount of
effort. I carefully recorded the amount of actual effort
in a number of cases and the story it tells concerning the
mental processes involved is the same as that told by the
time-curves.

Still another explanation is this: The monkeys learn
quickly, it is true, but not quickly enough for us to suppose
the presence of ideas, or the formation of associations among
them. For if there were such ideas, they should in the com-
plex acts do even better than they did. The explanation
then is a high degree of facility in the formation of associa-
tions of just the same kind as we found in the chicks, dogs
and cats.

Such an explanation we could hardly disapprove in any
case. Noone can from objective evidence set up a standard
of speed of learning below which all shall be learning with-
out ideas and above which all shall be learning by ideas.
We should not expect any hard and fast demarcation.

This whole matter of the rate of learning should be studied
in the light of other facts of behavior. My own judgment,
if I had nothing but these time-curves to rely on, would be
that there was in them an appearance of learning by ideas
which, while possibly explicable by the finer vision and
freer movements of the monkey in connection with ordinary
mammalian mentality, made it worth while to look farther
into their behavior. This we may now do.

What leads the lay mind to attribute superior mental
gifts to an animal is not so much the rate of learning as
the amount learned. The monkeys obviously form more

The Mental Life of the Monkeys 193

associations and associations in a greater variety than do the
other mammals. The improved rate assists, but another
cause of this greater number of associations is the general
physical activity of the monkeys, their constant movements
of the hands, their instinctive curiosity or tendency to fool
with all sorts of objects, to enjoy having sense-impressions,
to form associations because of the resulting sound or sight.
These mental characteristics are of a high degree of impor-
tance from the comparative point of view, but they cannot
be used to prove that the monkeys have free ideas, for a
large number of associations may be acquired after the
purely animal fashion.

What is of more importance is the actual behavior of the
animals in connection with the boxes. First of all, as has
been stated, all the monkey’s movements are more definite,
he seems not merely to pull, but to pull at, not merely to poke,
but to push at. He seems, even in his general random play,
to go here and there, pick up this, examine the other, etc.,
more from having the idea strike him than from feeling like
doing it. He seems more like a man at the breakfast table
than like a man in a fight. Still this appearance may be
quite specious, and I think it is likely to lead us to read
ideational life into his behavior if we are not cautious.
It may be simply general activity of the same sort as the
narrower activities of the cat or dog.

In the second place the monkeys often make special
movements with a directness which reminds one unavoid-
ably of human actions guided by ideas. For instance, No. 1
escaped from his cage one day and went directly across the
room to a table where lay a half of a banana which was in a
very inconspicuous place. It seemed as if he had observed
the banana and acted with the idea of its position fully in

mind. Again, on failing to pull a hook out, No. 1 im-
oO

194 Animal Intelligence

mediately applied his teeth, though he had before always
pulled it out with his hand. So again witha plug. It may
be that there is a special inborn tendency to bite at objects
pulled unsuccessfully. If not, the act would seem to show
the presence of the idea ‘get thing out’ or ‘thing come out’
and associated with it the impulse to use the teeth. We
shall see later, however, that in certain other circumstances
where we should expect ideas to be present and result in
acts they do not.

The fact is that those features in the behavior of the
monkeys in forming associations between the sight of a box
and the act needed to open it which remind us of learning
by ideas may also be possibly explained by general activity
and curiosity, the free use of the hand, and superior quick-
ness in forming associations of the animal sort. We must
have recourse to more crucial tests or at least seek evidence
from a number of different kinds of mental performances.
The first of these will naturally be their behavior toward
these same mechanisms after a long time-interval.

THE PERMANENCE OF ASSOCIATIONS IN THE CASE
oF MECHANISMS

My records are too few and in all but one case after too
short an interval to be decisive on the point of abrupt
transition from failure to success such as would characterize
an animal in whose mind arose the idea of a certain part of
the mechanism as the thing to be attacked or of a certain
movement as the fit one. The animals are all under ob-
servation in the Columbia Laboratory, however, and I
trust that later satisfactory tests may be made. No. 2
was not included in the tests because he was either unwell
or had become very shy of the boxes, entering them even

The Mental Life of the Monkeys 195

when the door was left open only after great delay. The
time-curves for the experiments performed will be found
on page 186 among the others. ‘The figures beside each pair
_ represent the number of days without practice.

The records show a decided superiority to those of the
cats and dogs. Although the number of trials in the original
tests were in general fewer in the case of the monkeys, the
retention of the association is complete in 6 cases out of 8
and is practically so in one case where the interval was
8 months.

EXPERIMENTS ON THE DISCRIMINATION OF
SIGNALS

My experiments on discrimination were of the following
general type: I got the animal into the habit of reacting
to a certain signal (a sound, movement, posture, visual
presentation or what not) by some well-defined act. In
the cases to be described this act was to come down from
his customary positions about the top of the cage, to a place
at the bottom. I then would give him a bit of food. When
this habit was wholly or partly formed, I would begin to
mix with that signal another signal enough like it so that
the animal would respond in the same manner. In the
cases where I gave this signal I would not feed him. Icould
then determine whether the animal did discriminate or not,
and his progress toward perfect discrimination in case he did.
If an animal responds indiscriminately to both signals (that
is, does not learn to disregard the ‘no food’ signal) it is
well to test him by using two somewhat similar signals,
after one of which you feed him at one place and after the ~
other of which you feed him at a different place.

If the animal profits by his training by acquiring ideas of

196 Animal Intelligence

the two signals and associates with them ideas of ‘food’
and ‘no food,’ ‘go down’ and ‘stay still,’ and uses these
ideas to control his conduct, he will, we have a right to
expect, change suddenly from total failure to differentiate
the signals to total success. He will or won’t have the ideas,
and will behave accordingly. The same result could, of
course, be brought about by very rapid association of the
new signal with the act of keeping still, a very rapid in-
hibition of the act of going down in response to it by virtue
of the lack of any pleasure from doing so.

For convenience I shall call the signals after which food
was given yes signals and those after which food was not
given vo signals. Signals not described in the text are
shown in Fig. 29, below. The progress of the monkeys in

oa Reade

105 8 108

=| ae
=
=

10 410

FIG. 29.

discriminating is shown by Figs. 30 and 31, on pages 199
and 201. In Figs. 30 and 31 every millimeter along the
horizontal or base line represents 10 trials with the signal.
The heights of the black surface represent the percentages
of wrong responses, 10 mm. meaning 100 per cent of

7

The Mental Life of the Monkeys 197

incorrect responses. Thus the first figure of the set, Left
hand, a, presents the following record: First 1o trials, all
wrong; of next 10, 7 wrong; of next 10, 6 wrong; of next
10, 7; of the next, 9; of the next, 9; of the next, 4; of
the next, none; of the next, 3; of the next, 2, and then
70 trials without an error.

I will describe some of the experiments in detail and then
discuss the graphic presentation of them all.

EXPERIMENTS WITH NO. 1

Having developed in No. 1 the habit of coming down
to the bottom of his cage to get a bit of food when he saw
me reach out and take such a bit from my desk, I tested
his ability to discriminate by beginning to use now one hand,
now the other, feeding him only when I used the left. I
also used different sets of words, namely, ‘I will give some
food’ and ‘They shall not have any.’ It will be seen later
that he probably reacted only to the difference of the hands.
The experiment is similar to that described on pages 129
and 130 of Chapter II. At the beginning, it should be
remembered, No. 1 would come down whichever hand was
used, no matter what was said, except in the occasional
cases where he was so occupied with some other pursuit
as to be evidently inattentive. He did come to associate
the act of going down with the one signal and the act of
staying still or continuing his ordinary movements with
the other signal. His progress in learning to do so is best
seen in the curves of his errors. To the ‘yes’ signal he re-
sponded correctly, except for the occasional lapses which I
just mentioned, from the start and throughout. With
the ‘no’ signal his errors were as shown in Fig. 30, a. The
break in the curve at 110 and 120 is probably not significant

198 Animal Intelligence

of an actual retrograde as the trials concerned followed an
eight days’ cessation of the experiments.

I next tried No. 1 with an apparatus exposing sometimes
a card with a diamond-shaped piece of buff-colored paper
on it and sometimes a card with a similar black piece.
The black piece was three fourths of an inch farther behind
the opening than the other. The light color was the ‘yes’
signal. The error curves for both signals are given, as No. 1
at the beginning of the experiment did not go down always
(Fig. 30, b and 0,).

I next tried No. 1 with the same apparatus but exposing
cards with YES and N in place of the buff and black dia-
monds. The record of the errors is given in Fig. 30, ¢ and ¢,.
At the start he came down halfway very often. This I
arbitrarily scored as an error no matter which signal it
was in response to. It should not be supposed that these
curves represent two totally new associations. It seems
likely that the monkey reacted to the position of the N
card in the apparatus (the same as that of the black dia-
mond card) rather than to the shape of the letters. On
putting the black diamond in front he was much confused.

I next gave No. 1 the chance to form the habits of coming
down when I rapped my pencil against the table twice and
of staying where he was when I rapped with it once. He
had 90 trials of each signal but failed to give evidence of
any different associations in the two cases.

Experiments of this sort were discontinued in the summer.
In October I tried No. 1 with the right and left hand ex-
periment, he being in a new room and cage, and I being
seated in a different situation. He came down at both sig-
nals and failed to make any ascertainable progress with the
no signal in 8o trials. (October 20-24.)

I then tried him with the black and buff diamonds, the

The Mental Life of the Monkeys 199

a, bain! a.

Left hand a

Lil bl

¢rear 6. @ buff b

Wk aa i

Yes ¢, Ku ie -™.
L
Front d vy un
L I WL
Light color e. oK Do y
1
© front f
U pels |
© back fa. Hitten’s record

Fic. 30.

200 Animal Intelligence

black being in front (October 25-29). The reaction to the
‘yes’ signal was perfect from the start. The progress with
the ‘no’ signal is shown in Fig. 30, d.

I then tried him with an apparatus externally of different
size, shape and color from that so far used, showing as the
‘yes’ signal a brown card and as the ‘no’ signal a white
and gold card one half inch farther back in the apparatus. ©
The ‘yes’ signal was practically perfect from the start. His
progress with the ‘no’ signal is shown in Fig. 30, e.

I then tried a still different arrangement for exposure, to
which, however, he did not give uniform attention.

I then tried cards 1 and r1o1, 1oz being in front and 1 in
back. 1 was the ‘yes’ signal. ‘Yes’ responses were perfect
from the start. For ‘no’ responses see Fig. 30, f. I then put
the ‘yes’ signal in front and the ‘no’ signal behind. ‘Yes’
responses perfect; for “no’ responses see Fig. 30, f, a.

From now on [I arranged the exposures in such a way that
there was no difference between the ‘yes’ and ‘no’ signals
in distance or surroundings.

The following list shows the dates, signals used, and the
figures on page 199 presenting the results. Where there is
only one figure drawn, it refers to progress with the ‘no’
signal, the ‘ yes’ signal being practically perfect from the start.

TABLE Io

‘Yes’ SIGNAL ‘No’ SIGNAL FIGURE
Nov. 13-15, 1900. 2 102 eas |
Nov. 14-16, 1900. 3 103 tn
Nov. 16-19, 1900. 4 104 h
Nov. 19, 1900. 5 105 J
Nov. 20, 1900. 6 106 k
Nov. 21, 1900. 7 107 l
Nov. 23(?) 1900. 8 108 m
Nov. 27-29, 1900. 9 10g n
Nov. 30,) 1900. IO IIo 0

The Mental Life of the Monkeys 201

Fig. 29 gives facsimiles of the different signals reduced to
one sixth their actual size. The drawing of ror is not accu-
rate, the outer ring being too thick.

EXPERIMENTS WITH No. 2

I first secured the partial formation of the habit of coming
down when I took a bit of food in my hand. I then used the
apparatus for exposing cards, YES in front being the ‘ yes’
signal and a circle at the back being the ‘no’ signal. I gave
No. 2 25 trials with the ‘yes’ signal and then began a regular

“ie 7

Right handA, Left hand A Box near
Palm upB E E
Feld up
A b.
Low front
FIG. 31.

experiment similar to those described. After about go trials
(November 9-12, 1900) there was no progress toward differ-
entiation of response, and it was evident from No. 2’s be-
havior that he was reacting solely to the movements of my
hand. So I abandoned the exposing apparatus and used
(November 11-13, 1900) as the ‘ yes’ signal the act of taking
the food with my left hand from a pile on the front of the box
and for the ‘no’ signal the act of taking food with my right
hand from a pile 4 inches behind that just mentioned.

202 Animal Intelligence

No. 2 did come to differentiate these two signals. The record
of his progress is given in Fig. 31 by A and Aj.

I then made a second attempt with the exposing appara-
tus, using cards 2 and 102 (November 6, 14-21). No. 2
did react to my movements in pulling the string but in over
100 trials made no progress in the direction of a differential
reaction to the ‘no’ signal. I then tried feeding him at each
signal, feeding him at the bottom of the cage as usual when
I gave the ‘yes’ signal and at the top when I gave the ‘no’
signal. After a hundred trials with the ‘no’ signal there
was no progress.

I then abandoned again the exposing apparatus and used
as signals the ordinary act of taking food with my left hand
(yes) and the act of moving my left arm from my right side
round diagonally (swinging it on my elbow as a center) and
holding the hand, after taking the food, palm up (no) (No-
vember 26, 27,1900). No. 2 did come to differentiate these
signals. His progress is given in the diagram in Fig. 31 en-
titled ‘Palm up’ (B).

I next used (November 27, 1900) as the ‘yes’ signal the
same act as before and for the ‘no’ signal the act of holding
the food just in front of the box about four inches below
the edge. No. 2’s progress is shown in Fig. 31 in the dia-
gram entitled ‘low front’ (C and C}).

IT next used (November 27-30) the same movement for
both ‘yes’ and ‘no’ signals save that as the ‘ yes’ signal I took
the food from a brown pasteboard box 3 by 3 byo.5, and as
the ‘no’ signal I took it from a white crockery cover two
inches in diameter and three eighths of an inch high which
was beside the box but three inches nearer me. No. 2’s
progress is shown in Fig. 31 in the diagram entitled ‘ Box
near’ (D).

I next used for the ‘yes’ signal the familiar act and for the

The Mental Life of the Monkeys 203

‘no’ signal the act of holding the food six inches above the
box instead of a quarter or a half an inch. The progress is
shown in Fig. 31, # and £,. I then tried taking the food
from a saucer off the front of the box for the ‘yes’ signal and
from a small box at the back for the ‘no’ signal. ‘Yes’ was
perfect from the start (10 trials given). ‘No’ was right
once, then wrong once, then right for the remaining eight.

EXPERIMENTS WITH No. 3

No. 3 was kept in a cage not half so big as those of 1 and 2.
Perhaps because of the hindrance this fact offered to forming
the habit of reacting in some definite way to ‘yes’ signals,
perhaps because of the fact that I did not try hand move-
ments as signals, there was no successful discrimination by
No. 3 of the yellow from the black diamond or of a card with
YES from a card with acircle onit. I tried climbing up to
a particular spot as the response to the ‘ yes’ signal and stay-
ing still as the response to the ‘no’ signal. I also tried in-
stead of the latter a different act, in which case the animal
was fed after both signals but in different places. In the
latter case No. 3 made some progress, but for practical
reasons I postponed experiments with him. Circumstances
have made it necessary to postpone such experiments in-
definitely.

PERMANENCE OF THE ABILITY TO DISCRIMINATE

No. 1 and No. 2 were tried again after intervals of 33 to 48
days. The results of these trials are shown in Fig. 32. Here
every millimeter along the base line represents one trial with
the ‘no’ signal (the ‘yes’ signals were practically perfect),
and failure is represented by a column 10 mm. high while

204 Animal Intelligence

success is represented by the absence of any column. Thus
the first record reads, ‘“‘No. 1 with signal 104 after 40 days
made 5 failures, then 2
successes, then 1 fail-
ure, then I success,
then 3 failures, then 1
success, then 1 failure,
then 3 successes, then
1 failure, then 10 suc-
cesses.” The third
record (106; 40 days)
reads, ‘‘ perfect success

iy oo in ten trials.”’

106 386 40 B 35 DISCUSSION OF RE-
SULTS

108 = 448 A 48

The results of all
these discrimination
experiments emphasize
the rapidity of forma-
tion of associations
amongst the monkeys,
107-82 Ai which appeared in their

ee behavior toward the
mechanisms. The suddenness of the change in many cases
is immediately suggestive of human performances. [If all
the records were like c, f, h, i, j, k, 1, m, B, E, and memory
trials 103, A, B, and C, one would have to credit the animals
with either marvelous rapidity in forming associations of
the purely animal sort or concede that from all the objective
evidence at hand they were shown to learn as human beings
would. One would have to suppose that they had clear

The Mental Life of the Monkeys - 205

ideas of the signals and clean-cut associations with those
ideas. The other records check such a conclusion.

In studying the figures we should remember that occa-
sional mistakes, say 1 in ro trials, are probably not significant
of incomplete learning but of inattention or of precipitate
action before the shutter had fairly exposed the card. We
~ must not expect that a monkey who totally fails to discrimi-
nate will always respond wrongly to the ‘no’ signal, or that
a monkey who has come to discriminate perfectly will always
respond rightly. A sudden drop from an average high level
of error to an average low level will signify sudden learning.
Where the failure was on the first trial of a series a few hours
or a day removed from the last series, I have generally repre-
sented the fact not by a column 1 mm. high and 1 mm.
broad, but by a single 10 mm. perpendicular. Seeiand A.
Such cases represent probably the failure of the animal to
keep his learning permanent rather than any general in-
ability to discriminate.

K was to some extent a memory trial of d (after over half
a year).

The experiment with 1o and 110 is noteworthy. Al-
though, as can be seen from the figures, the difference is ob-
vious to one looking at the white part of the figure, it is not
so to one looking at the black part. No. 1 failed to improve
appreciably in fifty trials, probably because his previous
experience had gotten him into the habit of attending to the
black lines.

Before arguing from the suddenness of the change from
failure to success we have to consider one possibility that I
have not mentioned, and in fact for the sake of clearness in
presentation have rather concealed. It is that the sudden
change in the records, which report only whether the animal
did or did not go down, may represent a more gradual

206 Animal Intelligence

change in the animal’s mind, a gradual weakening of the
impulse to go down which makes him feel less and less in-
clined to go down, though still doing so, until this weaken-
ing reaches a sort of saturation point and stops the action.
There were in their behavior some phenomena which might
witness to such a process, but their interpretation is so de-
pendent on the subjective attitude and prepossessions of the
observer that I prefer not to draw any conclusions from
them. On the other hand, records c, g,n, A and D seem
to show that gradual changes can be paralleled by changes
in the percentage of failures.

In the statement of conclusions I shall represent what
would be the effect on our theory of the matter in both cases,
(1) taking the records to be fairly perfect parallels of the
process, and (2) taking them to be the records of the summa-
tion points of a process not shown with surety in any meas-
urable objective facts. But I shall leave to future workers
the task of determining which case is the true one.

If we judge by the objective records themselves, we may
still choose between two views. (1) We may say that the
monkeys did come to have ideas of the acts of going down to
the bottom of the cage and of staying still, and that their
learning represented the association of the sense-impres-
sions of the two signals, one with each of these ideas, or pos-
sibly their association with two other ideas (of being fed
and of not being fed), and through them with the acts. Or
(2) we may say that the monkeys had no such ideas, but
merely by the common animal sort of association came to
react in the profitable way to each signal.

If we take the first view, we must explain the failure of the
animals to change suddenly in some of the experiments,
must explain why, for instance, No. 1 in gshould, after he had
responded correctly to the ‘no’ signal for 27 trials out of 30,

The Mental Life of the Monkeys 207

fail in one trial out of four for a hundred or more trials. If
the 27 successes were due to ideas, why was there regression ?
If the animal came to respond by staying still on seeing the
K (card 104), because that sight was associated with the idea
of no food or the idea of staying still, why did he, in his
memory trial, act sometimes rightly, sometimes wrongly, for
eleven trials after his acting rightly twice. If he stayed still
because the idea was aroused, why did he not stay still as
soon as he had a few trials to remind him of the idea? Itis
easy, one may say, to see why, with a capacity to select
movements and associate them with sense-presentations
very quickly, in cases where habit provides only two move-
ments for selection and where the sense-presentation is very
clear and simple, an animal should practically at once be
confirmed in the one act on an occasion when he does it
with the sense-impression in the focus of attention. It is
easy, therefore, to explain the sudden change in i, 1, m, B, C
and E. But our critic may add, “It is very hard to suppose
that an animal that learned by connecting the sight of a card
with the idea ‘stay still’ or the idea ‘no food,’ should be so
long in making the connection as was the case in some of
these experiments, should take 10, 20 or 4o trials to change
from a high percentage of wrong to a high percentage of
right reactions.”

If we take the second view, we have to face the fact that
many of the records are nothing like the single one we have
for comparison, that of the kitten shown in Fig. 30, and that
the appeal to a capacity to form animal associations very
quickly seems like a far-fetched refuge from the other view
rather than a natural interpretation. If we take the rec-
ords to be summation points in a more gradual process, this
difficulty is relieved.

If further investigation upheld the first view, we should

208 Animal Intelligence

still not have a demonstration that the monkeys habitually
did learn by getting percepts and images associated with
sense-impressions, by having free ideas of the acts they per-
formed; we should only have proved that they could under
certain circumstances.

The circumstances in these experiments on discrimination
were such as to form a most favorable case. The act of
going down had been performed in all sorts of different con-
nections and was likely to gain representation in ideational
life; the experience ‘ bit of banana’ had again been attended
to as a part of very many different associations and so would
be likely to develop into a definite idea.

These results then do not settle the choice between three
theories: (1 a) that they were due to a general capacity for
having ideas, (1 6) that they were due to ideas acquired by
specially favoring circumstances, (2) that they were due to
the common form of association, the association of an im-
pulse to an act with a sense-impression rather roughly felt.

It would be of the utmost interest to duplicate these ex-
periments with dogs, cats and other mammals and compare
the records. Moreover, since we shall find (1 a) barred out
by other experiments, it will be of great interest to test the
monkeys with some other type of act than discrimination
to see if, by giving the animal experience of the act and result
involved in many different connections, we can get a rate
of speed in the formation of a new association comparable to
the rates in some of these cases.

Of course here, as in our previous section, the differences
in the sense-powers of the monkeys from those of the kitten
which I have tested with a similar experiment may have
caused the difference in behavior. Focalized vision lends
itself to delicate associations. Perhaps if one used the sense
of smell, or if the dogs and cats could, preserving their same

The Mental Life of the Monkeys 209

mental faculties in general, add the capacity for focalized
vision, they would do as well as the monkeys.

EXPERIMENTS ON THE INFLUENCE OF TUITION

The general aim of these experiments was to ascertain
whether the monkeys’ actions were at all determined by the
presence of free ideas and if so, to what extent. The ques-
tion is, ‘‘ Are the associations which experience leads them to
form, associations between (1) the idea of an object and (2)
the idea of an act or result and (3) the impulses and act itself,
or are they merely associations between the sense-impres-
sion of the object and the impulse and act?”’ Can a mon-
key learn and does he commonly learn to do things, not by
the mere selection of the act from amongst the acts done by
him, but by getting some idea and then himself providing
the act because it is associated in his mind with that idea.
If a monkey feels an impulse to get into a box, sees his arm
push a bar and sees a door fall open immediately thereafter
and goes into the box enough times, he has every chance to
form the association between the impulse to get into the
box and the idea ‘arm push bar,’ provided he can have such
an idea. If his general behavior is due to having ideas
connected with and so causing his acts, he has had chance
enough to form the association between the idea ‘push at’
and the act of pushing. If then a monkey forms an asso-
ciation leading to an act by being put through the act, we
may expect that he has free ideas. And if he has free ideas
in general in connection with his actions, we may expect him
to so form associations. So also if a monkey shows a gen-
eral capability to learn from seeing another monkey or a
human being doa thing. A few isolated cases of imitation,
however, might witness not to any general mental quality,

P

210 Animal Intelligence

but only to certain instincts or habits differing from others
only in that the situation calling forth the act was the same
act performed by another.

If the monkeys do not learn in these ways, we must, until
other evidence appears, suppose them to be in general desti-
tute of a life of free ideas, must regard their somewhat am-
biguous behavior in learning by their own unaided efforts
as of the same type as that of the dogs and cats, differing
only in the respects mentioned on pages 190 and ror.

The general method of experimentation was to give mon-
keys who had failed of their own efforts to operate some
simple mechanism, a chance to see me do it or see another
monkey do it or to see and feel themselves do it, and then
note any change in their behavior. The chief question is
whether they succeed after such tuition when they have
failed before it, but the presence of ideas would also be
indicated if they attacked, though without success, the
vital point in the mechanism when they had not done so
before. On the other hand, mere success would not prove
that the tuition had influenced them, for if they made a dif-
ferent movement or attacked a different spot, we could not
attribute their behavior to getting ideas of the necessary act.

The results of the experiments as a whole are on their face
value a trifle ambiguous, but they surely show that the mon-
keys in question had no considerable stock of ideas of the
objects they dealt with or of the movements they made and
were not in general capable of acquiring, from seeing me or
one of their comrades attack a certain part of a mechanism
and make a certain movement, any ideas that were at all
efficacious in guiding their conduct. They do not acquire
or use ideas in anything that approaches the way human
adults do. Whether the monkeys may not have some few
ideas corresponding to habitual classes of objects and acts

The Mental Life of the Monkeys 211

is a different question. Such may be present and function
as the excitants of acts.

It is likely that this question could have been definitely
solved if it had been possible for me to work with a larger
number of animals. With enough subjects one could use
the method mentioned on page 105 of Chapter II, of
giving the animals tuition in acts which they would
eventually do themselves without it, and then leaving them
to their efforts, noting any differences in the way they
learned from that in which other subjects who had no tui-
tion learned the same acts. The chief of such differences to
note would be differences in the time of their first trial, in the
slope of the time-curve and in the number of useless acts.

It would also be possible to extend experiments of the
type of the (on chair) experiment, where a subject is given
first a certain time (calculated by the experimenter to be
somewhat less than would be needed for the animal to hit
upon the act) and if he does fail is then given certain tuition
and then a second trial. The influence of the tuition is esti-
mated by the presence or absence of cases where after tuition
the act is done within the time.

There is nothing necessarily insoluble in the problem.
Given ten or twenty monkeys that can be handled without
any difficulty and it could be settled in a month.

With this general preface we may turn to the more special
questions connected with the experiments on imitation of
human acts and of the acts of other monkeys and on the for-
mation of associations apart from the selection of impulses.

IMITATION OF HuMAN BEINGS

It has been a common opinion that monkeys learned
to do things from seeing them done by human beings.

212 Animal Intelligence

We find anecdotes to that effect in fairly reputable
authors.

Of course, such anecdotes might be true and still not prove
that the animals learned to do things because they saw them
done. The animal may have been taught in other ways to
respond to the particular sights in question by the particular
acts. Or it may have been in each case a coincidence.

If a monkey did actually form an association between a
given situation and act by seeing some one respond to that
situation by that act, it would be evidence of considerable
importance concerning his general mental status, for it
would go to show that he could and often did form asso-
ciations between sense-impressions and ideas and between
ideas and acts. Seeing some one turn a key in a lock might
thus give him the idea of turning or moving the key, and this
idea might arouse the act. However, the mere fact that a
monkey does something which you have just done in his
presence need not demonstrate or even render a bit more
probable such a general mental condition. For he perhaps
would have acted in just the same manner if you had offered
him no model. If you put two toothpicks on a dish, take
one and put it in your mouth, a monkey will do the same, not
because he profits by your example, but because he in-
stinctively puts nearly all small objects in his mouth. Be-
cause of their general activity, their instinctive impulses to
grab, drop, bite, rub, carry, move about, turn over, etc., any
novel object within their reach, their constant movement
and assumption of all sorts of postures, the monkeys per-
form many acts like our own and simulate imitation to a far
greater extent than other mammals.

Even if a monkey which has failed of itself to do a certain
thing does it after you have shown him the act, there need
be no reason to suppose that he is learning by imitation,

The Mental Life of the Monkeys 252

forming an association between the sight of the object and
the act towards it through an idea gained from watching
you. You may have caused his act simply by attracting his
attention to the object. Perhaps if you had pointed at it or
held it passively in your hand, you would have brought to
pass just the same action on his part. ‘There are several
cases among my records where an act which an animal failed
totally to do of himself was done after I had so attracted his
attention to the object concerned.

Throughout all the time that I had my monkeys under ob-
servation I never noticed in their general behavior any act
which seemed due to genuine imitation of me or the other
persons about. I also gave them special opportunities to
show such by means of a number of experiments of the fol-
lowing type: where an animal failed by himself to get into
some box or operate some mechanism, I would operate it in
his presence a number of times and then give him a chance to
profit by the tuition. His failure might be due to (z) the
absence of instinctive impulses to make the movement in
that situation, (2) to lack of precision in the movement, (3)
to lack of force, or (4) to failure to notice and attack some
special part of the mechanism. An instance of (1) was the
failure to push away from them a bar which held a door;
an instance of (2) was the failure to pull a wire loop off a
nail; an instance of (2) or (3) was the failure to pull up a
bolt ; an instance of (4) was the failure to pull up an inside
bar. Failures due to (3) occur rarely in the case of such
mechanisms as were used in my investigations.

The general method of experiment was to make sure that
the animal would not of itself perform a certain act in a cer-
tain situation, then to make sure that his failure could not
be remedied by attracting his attention to the object, then
to perform the act for him a number of times, letting him get

214 Animal Intelligence

each time the food which resulted, and finally to see whether,
having failed before the tuition, he would succeed after it.
This sounds very simple, but such experiments are hard to
carry out satisfactorily. If you try the animal enough times
by himself to make quite sure that he will not of himself hit
upon the act, you are likely to form in him the habit of
meeting the particular situation in question with total dis-
regard. His efforts having failed so often may be so in-
hibited that you could hardly expect any tuition to give
them new life. The matter is worse if you add further
enough trials to assure you that your attracting his atten-
tion to it has been unavailing. On the other hand, if you
take failure in five or ten minutes to mean inability, and
from subsequent success after imitation argue that imitation
was efficient, you have to face the numerous cases where
animals which have failed in ten minutes have succeeded in
later unaided trials. With dogs and cats this does not much
matter, because they aresteady performers, and their conduct
in one short trial tells you what to expect with some proba-
bility. But the monkeys are much more variable and are
so frequently distracted that one feels much less confidence
in his predictions. Moreover, you cannot be at all sure of
having attracted a monkey’s attention to an object unless he
does touch it. Suppose, for example, a monkey has failed
to even touch a bar though you have put a bit of food on it
repeatedly. It is quite possible that he may look at and
take the food and not notice the bar, and the fact that after
such tuition he still fails to push or pull the bar may mean
simply that it has not caught his notice. I have, therefore,
preferred in most cases to give the animals only a brief
period of trial to test their ability by their own unaided
efforts and to omit the attempts to test the efficacy of at-
tracting their attention to the vital point in the mechanism.

The Mental Life of the Monkeys 215

This makes the results appear less elegant and definitive but
really increases their value for purposes of interpretation.

The thoughtful reader will not expect from my experi-
ments any perfectly rigorous demonstration of either the
presence or the absence of imitation of human acts as a
means of learning. The general trend of the evidence, it
seems to me, is decidedly towards justifying the hypothesis
that the monkeys did not learn acts from seeing me do
them.

I will first describe a sample experiment and then present
a summary of all those made.

On January 12th I put box Epsilon (push down) in No.
3’s cage, the door of the box being open. I put a bit of food
in the box. No. 3 reached in and took it. This was re-
peated three times. I then put in a bit of food and closed the
door. No. 3 pulled and bit the box, turned it over, fingered
and bit at the hole where the lever was, but did not succeed
in getting the door open. After ten minutes I took the box
out. Later I took No. 3 out and let him sit on my knees (I
sitting on the floor with the box in front of us). I would
then put my hand out toward the box and when he was
looking at it would insert my finger and depress the lever
with as evident a movement as I could. The door, of
course, opened, and No. 3 put his arm in and took the
bit of food. I then put in another, closed the door and de-
pressed the lever as before. No. 3 watched my hand pretty
constantly, as all his experiences with me had made such
watching profitable. After ten such trials he was put back
in the cage and the box put in with a large piece of food in it
and its door closed. No. 3 failed in five minutes and the
box was taken out. He was shown fifteen times more and
then left to try himself. I tried him for a couple of minutes
under just the same circumstances as existed during the

216 Animal Intelligence

tuition, z.e. he on the floor by me, the box in front. In this
trial and in a five-minute trial inside his cage he failed to
open the door or to differ in any essential respect from his
behavior before tuition.

No. 1 saw me do g different acts and No. 3, 7, which they
had failed of themselves to do.t. After from 1 to 40 chances
to imitate me they still failed to operate at all 11 of these
mechanisms. In the case of 3 out of 5 that were worked
the act was not the same as that taught. No.1, who saw
me pull a nail out by taking the end of it and pulling the nail
away from the box, himself put his hand round the nail and
wriggled it out by pulling his hand back and forth. No. 3,
who saw me pull a bolt up with my fingers, succeeded by
jerking and yanking the door until he shook the bolt up.
He saw me pull a hook out of an eye, but he succeeded by
pulling at a bar to which it was attached. In the case of
one of the two remaining acts (No. 3 with nail chute) the act
was done once and never again, though ample opportunity
was given and tuition continued. It could, therefore,
hardly have been due to an idea instilled by the tuition.
The remaining case, No. 1, with loop, must, I think, be at-
tributed to accident, especially since No. 3 failed to profit

1 The acts and the number of chances to see me do each and the results
were as follows; details can be found on the table on page 226. F = failed
after tuition.

No.1.—MM_ a1F No. 3. — Theta 25 did in 3.00.
Theta 5F QQ 40 F
QQ 10 F Gamma 30 F
RR 4F
W 9 did in .22 Epsilon 25 F
Delta 15 F OOWG) 25
Epsilon 40 F QQ (c) 20F, did in 1.30, F, 5 F,
5 F
QQ (f) 15 F QQe 5 F, did in 2.00

QQ (c) 1 did in 2.20

The Mental Life of the Monkeys 217

by precisely the same sort of tuition with precisely the same
act.

Nor is there any evidence to show that although tuition
failed to cause successes where unaided effort failed, it yet
caused attempts which would not otherwise have occurred.
Out of fifteen cases where such might have appeared, there
were only three where it is possible to claim that they did.
No one of these three is a sure case. With RR (wood plug)
No. 1 did seem to pull the plug more definitely after seeing
me than before. With QQ (c) (nail chute) and MM (bolt -
at top) he may possibly have done so.

In 5 cases I tried the influence of seeing me make the
movement on animals who had done the act of themselves,
the aim being to see whether there would be a marked short-
ening of the time, a change in their way of operating the
mechanism or an attempt at such change. I will give the
essential facts from the general table on pages 226-229.

(a) No. 1 had succeeded in pulling in the box by the upper
string in OOO (upper string box) in 2.20 and then failed in
3.00. I showed him 4 times. He failed in 10. I showed
him 4 more times. He failed in 10. I showed him 4 more
times. Hesucceededin.20. No change in manner of act or
objects attacked, though my manner was different from his.

(b) No. 1 had succeeded in QQ (a) (chute bar) in 8.00. I
showed him 20 times. He failed in 10. I showed him 10
more times. He succeeded in 2.00. I showed him 10 more
times. He succeeded in 50 seconds. No change in his
manner of performance or in the object attacked, though my
manner was different from his.

(c) No. 1 had succeeded in 3.00, .25, .07, .25, .20, .o6 and
.o9 with QQ (b) (chute bar double) and then failed in 5.00.
I showed him to times. He then failed in 5 twice, succeeded
in 3.00, and failed in 5 again. No change in manner of per-

218 Animal Intelligence

formance or in the object attacked, though my manner was
different from his.
(d) No. 3 had the following record in box Delta: —

2.00 (pushed with head)
3.20 (pushed with head)

30 F

10 F

10 F
2.10 (pulled wire and door).

I showed him 20 times by pushing the bar to the right with
my finger. He succeeded in 8.00 and 8.00 by pulling the
wire and the door. No change in object attacked.

(e) No. 2 had failed twice in 5 with chute QQ (ff) (chute
string wire) and succeeded once in 2.00 by a strong pull on
the wire itself, not the loop. I showed him 5 times, pulling
the loop off the nail. He then failed in 5. There was no
change in the objects attacked.

These records show no signs of any influence of the tuition
that are not more probably signs of something else. We
cannot attribute the rapid decrease in time taken in (8) to
the tuition until we know the time-curve for the same
process without tuition.

The systematic experiments designed to detect the pres-
ence of ability to learn from human beings are thus practi-
cally unanimousagainst it. So, too, was the general behavior
of the monkeys, though I do not consider the failure of the
animals to imitate common human acts as of much impor-
tance save as a rebuke to the story-tellers and casual ob-
servers. The following facts are samples: The door of No.
1’s cage was closed by an iron hoop with a slit in it through
which a staple passed, the door being held by a stick of wood
thrust through the staple. No. 1 saw me open the door of

I'he Mental Life of the Monkeys 219

his and other cages by taking out sticks hundreds of times,
but though he escaped from his cage a dozen times in other
ways, he never took the stick out and to my knowledge never
tried to. I myself and visitors smoked a good deal in the
monkeys’ presence, but a cigar or cigarette given to them
was always treated like anything else.

IMITATION OF OTHER MONKEYS

It would theoretically seem far more likely that the mon-
keys should learn from watching each other than from watch-
ing human beings, and experimental determinations of such
ability are more important than those described in the last
section as contributions both to genetic psychology and to
natural history. I regret that the work I have been able to
do in the study of this phase of the mental life of the mon-
keys has been very limited and in many ways unsatisfactory.

We should expect to find the tendency to imitation more
obvious in the case of young and parents than elsewhere. I
have had no chance to observe such cases. We should ex-
pect closely associated animals, such as members of a com-
mon troop or animals on friendly terms, to manifest it more
than others. Unfortunately, two of my monkeys, by the
time I was ready to make definite experiments, were on terms
of war. The other had then become so shy that I could not
confidently infer inability to do a thing from actual failure
to do it. He showed no evidence of learning from his
mates. I have, therefore, little evidence of a quantitative
objective nature to present and shall have in the end to ask
the reader to take some opinions without verifiable proofs.

My reliable experiments, five in number, were of the fol-
lowing nature. A monkey who had failed of himself (and
often also after a chance to learn from me or from being put

220 Animal Intelligence

through the act) would be put where he could see another
do the act and get a reward (food) for it. He would then be
given a chance to do it himself, and note would be taken of
his success or failure, and of whether his act was the same
as that of his model in case he succeeded, and of whether he
tried that act more than before the tuition in case he tried
it and failed. The results are given in Table 11.

In the fourth experiment No. 1 showed further that the
tuition did not cause his successes in that after some suc-
cesses further tuition did not improve him.

There is clearly no evidence here of any imitation of No. 1
by No. 3. There was also apparently nothing like purposive
watching on the part of No.3. He seemed often to see No.
r open the box or work the chute mechanism, but without
special interest.

This lack of any special curiosity about the doings of their
own species characterized the general behavior of all three of
my monkeys and in itself lessens the probability that they
learn much from one another. Nor did there appear, in the
course of the three months and more the animals were to-
gether, any signs of imitation. There were indeed certain
notable instances of the lack of it in circumstances which
one would suppose would be favorable cases for it.

For instance: No. 2 was very timid. No. 1 was perfectly
tame from the first day No. 2 was with me, and No. 3 be-
came tameshortly after. No.2saw Nos. 1 and 3 come to me,
be played with, fed and put through experiments, yet he
never did the same nor did he abate a jot or tittle from his
timidity save in so far as I sedulously rewarded any chance
advances of his. Conversely No. 1 and No. 3 seemed un-
influenced by the fear and shyness of No. 2. No.2’s cage
was between No. 1’s and No. 3’s, and they were for three
weeks incessantly making hostile demonstrations toward

221

The Mental Life of the Monkeys

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222 Animal Intelligence

each other, jumping, chattering, scowling, etc. No. 2
never did anything of the sort. Again, seeing No. 3 eat
meat did not lead No. 1 to take it; nor did seeing No. 1
retreat in fright from a bit of absorbent cotton lead No. 3
to avoid it.

Nothing in my experience with these animals, then, favors
the hypothesis that they have any general ability to learn to
do things from seeing others do them. ‘The question is still
an open one, however, and a much more extensive study of it
should be made, especially of the possible influence of imita-
tion in the case of acts already familiar either as wholes or
in their elements.

LEARNING APART FROM Motor IMPULSES

The reader of my monograph, ‘Animal Intelligence,’ will
recall that the experiments there reported seemed to show
that the chicks, cats and dogs had only slight and sporadic,
if any, ability to form associations except such as contained
some actual motor impulse. They failed to form such asso-
cilations between the sense-impressions and ideas of move-
ments as would lead them to make the movements with-
out having themselves previously in those situations given
the motor impulses to the movements. They could not,
for instance, learn to do a thing from having been put
through it by me.

The monkeys Nos. 1 and 3 were tested in a similar way
with a number of different acts. The general conclusion
from the experiments, the details of which will be given
presently, is that the monkeys are not proved to have the
power of forming associations of ideas to any greater extent
than the other mammals, that they do not demonstrably
learn to do things from seeing or feeling themselves make

The Mental Life of the Monkeys 223

the movement. An adult human being whose hand was
taken and made to push in a bar or pull back a bolt would
thereby learn to do it for himself. Cats and dogs would
not, and the monkeys are not proved to doso. On the
other hand, it is impossible for me to say, as of the dogs and
cats, that the monkeys are proved not to do so. Ina few
cases the animals did perform acts after having been put
through them which they had failed to perform when left
to their own trial and success method. In the majority of
cases they did not. And in some of these latter cases fail-
ure seemed so improbable in case the animal really had the
power of getting an idea of the act and proceeding from idea
to execution, that one is inevitably led to some explanation
for the few successes other than the presence of ‘ideas.’
The general manner of making these experiments was like
that in the case of the cats and dogs, save that the monkey’s
paw was used to open the box from the outside instead of
from the inside, and that the monkeys were also put through
the acts necessary to operate some of the chute mechanisms.
Tests parallel to that of comparing the behavior of kittens
who had themselves gone into boxes with those who were
dropped in by me were made in the following manner. I
would carry a monkey from his cage and put him in some
conspicuous place (e.g. on the top of a chair) and then give
him a bit of food. This I would repeat a number of times.
Then I would turn him loose in the room to see whether he
had acquired an idea of being on the chair which would lead
him to himself go to the chair. I would, in order to tell
whether his act, in case he did so, was the result of random
activities or was really due to his tuition, leave him alone for
5 or 10 minutes before the tuition. If he got on the chair
afterwards when he had not before, or got on it much
sooner, it would tend to show that the idea of getting food

224 Animal Intelligence

on that chair was present and effective. We may call these
last the ‘on chair’ type of experiments.

A sample experiment with a box is the following :—

On January 4, 1901, box Delta (push back) was put in No.
1’s cage. He failed in 5, though he was active in trying to
get in for about 4 minutes of the time and pulled and pushed
the bar a great deal, though up and down and out instead of
back. In his aimless pushings and pullings he nearly suc-
ceeded. He failed in 5 ina second trial also. I then opened
the door of the cage, sat down beside it, held out my hand,
and when he came to me took his right paw and with it (he
being held in front of the box) pushed the bar back (and
pulled the door open in those cases when it did not fall open
of itself). He reached in and took the food and went back
to the top of his cage and ate it. (No. 1 generally did this,
while No. 3 generally stayed by me.) I then tried him alone;
result 10 F; no activity at all. On January 5th I put the
box in; result 1o F. He was fairly active. He pulled at
the bar but mostly from a position on the top of the box
and with his left hand; no attempts like the one I had tried
to teach him. Being left alone he failed in 5. Being tried
again with the door of the cage open and me sitting as I had
done while putting him through the act, he succeeded in 7.00
by pushing the bar with his head in the course of efforts to
poke his head in at the door. I then put him through the
act ro times and left him to himself. He failed in 5.00;
no activity. I then sat down by the cage as when teaching
him. He failed in 5; little activity. Later in the day I put
him through the act ro times and then left him to himself.
He failed in 5; little activity. Isat down as before. He
failed in five; little activity. On January 6th I put him
through the act ro times and then left him. He failed in
10. This was repeated later in the day with the same result.

The Mental Life of the Monkeys 225

Record: — By himself, 10 F. Put through 80 times. F 65
(a) [the (a) refers to a note of his unrepeated chance success
with his head]. No similar act unsuccessfully attempted.
Influence of tuition, none.

With the chute mechanisms the record would be of the
same nature. With them I put the animal through gener-
ally by taking his paw, held out through the wire netting of
the cage, and making the movement with it. In one ex-
periment (No. 3 with QQ chute) the first 58 trials were made
by taking the monkey outside the cage and holding him in-
stead of having him put his paw through the netting for me
to take.

Many of the experiments were with mechanisms which
had previously been used in experiments concerning the
ability to learn from seeing me operate them. And the
following Table (12) includes the results of experiments of
both sorts. The results of experiments of the ‘on chair’
type are in Table 13. Incases where the same apparatus
was used for both purposes, the sort of training which was
given first is that where an A is placed.

In the first four experiments with No. 1 there was some
struggling and agitation on his part while being held and put
through the act. After that there was none in his case ex-
cept occasional playfulness, and there was never any with
No. 3 after the first third of the first experiment. The
monkeys soon formed the habit of keeping still, because it
was only when still that I put them through the act and that
food resulted. After you once get them so that they can
be held and their arms taken without their clinging to you,
they quickly learn to adapt themselves to the experiments.

With No. 1, out of 8 cases where he had of himself failed
(in five of the cases he had also failed after being shown by
me), he succeeded after being put through (13, 21, 51, 10, 7,

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Animal Intelligence

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230 Animal Intelligence

80, and 10 times) in two cases (QQ (chute) and RR (wood
plug). The act was unlike the one taught him in the former
case.

In only one case (bolt at top) out of eight was there pos-
sibly any attempt at the act after he had been put through
which had not been made before. The ‘yes or ?’ in the
table with RR was a case occurring after the imitation of me
but before the putting No. 1 through.

Out of 6 cases where he had himself failed, No. 3 suc-
ceeded (after being put through 113, 23, 20, 10, 10, 20 and 10
times) in 3 cases (chute bar, push down and bar inside).
The act was dissimilar in all three cases, bearing absolutely
no resemblance in one case. There was no unsuccessful
attempt at the act taught him in any of the cases. With
the chute he did finger the bar after tuition where he had
not done so before, but it was probably an accidental result
of his holding his hand out toward it for me to take as he had
formed the habit of doing. In the case of box Epsilon
(push down), with which he succeeded by pushing his hand
in above the lever (an act which though unlike that taught
him might be by some considered to be due to an idea
gained from the tuition), he failed entirely after further
tuition (15 times).

Like the dogs and cats, then, the monkeys seemed unable
to learn to do things from being put through them. We
may now examine those which they did do of themselves be-
fore tuition and ask whether they learned the more rapidly
thereby or modified their behavior in ways which might be
due to the tuition. There are too few cases and no chance
for comparison on the first point; on the second the records
are unanimous in showing no change in the method of oper-
ating the mechanisms due to the tuition.

As in Table 9, figures followed by F mean that in that

The Mental Life of the Monkeys

231

length of time the animal failed. Figures without an F de-
note the time taken by the animal to operate the mechanism.

As a supplement to Table 12 I have made a summary of
the cases where the animals did succeed after tuition, that
shows the nature of the act shown them as compared with
the act they made use of.

APPARATUS

O00

QQ

QQ (c)

Delta

Theta

SUPPLEMENT TO TABLE 12

MODEL GIVEN OR ACT
PUT THROUGH

To pull upper
string.

To push bar in.

To pull plug out
with right hand.

To pull loop off nail
Fwith right hand.

To pull bar around
toward him.

To pull bar around
toward him in
2} continuous
revolutions.

To take nail and
pull directly out-
ward.

To push bar to right
with right hand.

To pull bolt up with
right hand.

Act oF No.1

Pulled both strings

alternately, but
upper enough
more to succeed.

Inserted fingers be-
tween bar and its
slot and pulled
and pushed
vaguely.

Pulled and bit.

Similar.

Pulled back and
forth indiscrimi-
nately.

Pulled back and
forth indiscrimi-
nately.

Pulled back and
forth.

Act or No. 3

Pulled back and
forth indiscrimi-
nately.

Similar or nearly so.

Did before tuition
by pulling wire;
after tuition by
chance movement
of head.

Pulled door and
worked bolt loose.

232 Animal Intelligence

MODEL GIVEN OR ACT
APPARATUS Gee SS Act oF No. r Act oF No. 3

Epsilon | To stand in front, Inserted arm in gen-
insert fingers of eral activity while
right hand and on top of the box.
press lever down.

QQ (e) To pull hook down. Pulled at the lever

and hook in a
general attack on
the apparatus.

QQ (ff) | To pull wire loop Pulled outward on
off nail with right the lever which
hand. pushed the ba-

nana down the
chute so hard as
to pull it off its

pivot.
WW To stand on top of Pulled at door until
box, reach right bar worked} out
hand down and of its catch.

pull bar up.

I have kept the results of the tests of the ‘on chair’ type
separate from the others because they may be tests of a dif-
ferent thing and surely are subject to different conditions.

They were tests of the animals’ ability to form the habit of
going to a certain place by reason of having been carried
there and securing food thereby. I would leave the animal
loose in the room, and if he failed in 5 or 10 minutes to go to
the place of his own accord, would put him back in his cage;
if he did go of his own accord, I would note the time. Then
I would take him, carry him to the place, and feed him.
After doing this 10 times I would turn him loose again and
see whether the idea of being fed in such and such a place was
present and active in making him go to the place. Insuch
tests we are absolutely sure that the animal can without any
difficulty perform the necessary movements and would in

The Mental Life of the Monkeys 233

case the proper stimulus to set them off appeared, if, for
instance, a bit of food on one of the places to which he was to
go caught his eye. In so far forth the tests were favorable
cases for learning. On the other hand, the situation asso-
ciated with getting food may have been in these cases not
the mere ‘being on box’ but the whole previous experience
‘being carried while clinging and being put or let jump on a
box.’ In this respect the tests may have been less favor-
able than the acts where getting food was always the direct
sequent of the act of going into the box.

The experiments were :—

A. Carrying the animal and putting him on a chair.

B. Carrying theanimal and putting him on a pile of boxes.

C. Carrying the animal and putting him on the top of a
sewing machine.

D. Carrying the animal and putting him on the middle of
a board 6 feet long, stretched horizontally across the room,
3 feet from the floor.

EK. Carrying the animal and putting him on the side of the
cage, head down.

The results are given in Table 13.

The size of the room in which I worked and other practical
difficulties prevented me from extending these experiments.
As they stand, no stable judgments can be inferred from
them. It should be noted that in the successful cases there
were no other signs of the presence of the idea ‘food when
there’ than the mere going to acertain place. The animal
did not wait at the place more than a second or two, did not
look at me or show any signs of expecting anything.

Although, as I noted in the early part of this monograph,
there were occasionally phenomena in the general behavior
of the monkeys which of themselves impressed one as being
suggestive of an ideational life, the general run of their

234 Animal Intelligence

TABLE 13
EXPERIMENT RESULTS BE- | Nouwper oF TIMES RESULTS
AND DATE ANIMAL ORE ea PUT THROUGH igcepirs
ING TRAINING
A. Jan. 22, 1901 No. 1. 5F 10 1.00
3.00
Jan. 22, 1901 No. 1. 5sF ie) im.
3-30
Jan. 23, 1901 No. 3. 5F Io 3.30
ip
B. Jan. 26, 1901 INO: a: 10 F roand 5 Io F5F
No. 3 5 F Io oe
Io 5F
C. Jan. 27, 1901 No. 1. 5 F 10 3.00
D. Jan. 27, 1901 No. 1. 3.20 Io 5F
E. Jan. 26, 1901 No. 3. 5 F 5 ce

learning apart from the specific experiments described was
certainly confined to the association of impulses of their
own with certain situations. The following examples will
suffice : —

In getting them so that they would let themselves be han-
dled it was of almost no service to take them and feed them
while holding them or otherwise make that state pleasant
for them. By far the best way is to wait patiently till they
do come near, then feed them; wait patiently till they do
take hold of your arm, then feed them. If you do take them
and hold them partly by force, you must feed them only
when they are comparatively still. In short, in taming
them one comes unconsciously to adopt the method of re-
warding certain of their impulses rather than certain con-
ditions which might be associated in their minds with ideas,
had they such.

After No. 1 and No. 3 had both reached a point where
both could hardly be gotten to leave me and go back into

The Mental Life of the Monkeys 235

their cages or down to the floor of the room, where they evi-
dently enjoyed being held by me, they still did not climb
upon me. The idea of clinging to me was either absent or
impotent to cause them to act. What they did do was, in
the case of No. 1, to jump about, pawing around in the
air, until I caught an arm or leg, to which stimulus he had
by dint of the typical sort of animal association learned to
react by jumping to my arm and clinging there; in the case
of No. 3, to stand still until I held my arm right in front of
him (if he were in his cage) or to come and stand on his
hind legs in front of me (if he were out on the floor). In
both cases No. 3’s act was one which had been learned by
my rewarding his impulses. I often tried, at this period of
their intimacy with me, this instructive experiment. The
monkey would be clinging to me so that I could hardly
tear him away. I would do so, and he would, if dropped
loose from me, make no efforts to get back.

I have already mentioned my failure to get the animals to
put out their right hands through the netting after they had
long done so with their left hands. With No. 3 I tried put-
ting my fingers through and poking the arm out and then
making the movement with it. He profited little if any by
this tuition. Had I somehow induced him to do it himself,
a few trials would have been sufficient to get the habit well
under way.

Monkey No. 1 apparently enjoyed scratching himself.
Among the stimuli which served to set off this act of scratch-
ing was the irritation from tobacco smoke. If any one
would blow smoke in No. 1’s face, he would blink his eyes
and scratch himself, principally in the back. After a time
he got in the habit of coming to the front of his cage when
any one was smoking and making such movements and
sounds as in his experience had attracted attention and

236 Animal Intelligence

caused the smoker to blow in his face. He was often given
a lighted cigar or cigarette to test him for imitation. He
formed the habit of rubbing it on his back. After doing so
he would scratch himself with great vigor and zest. He
came to do this always when the proper object was given
him. I have recounted all this to show that the monkey
enjoyed scratching himself. Vet he apparently never
scratched himself except in response to some sensory stimulus.
He was apparently incapable of thinking ‘scratch’ and so
doing. Yet the act was quite capable of association with
circumstances with which as a matter of hereditary organi-
zation it had no connection. For by taking a certain well-
defined position in front of his cage and feeding him when-
ever he did scratch himself I got him to always scratch
within a few seconds after I took that position.

GENERAL MENTAL DEVELOPMENT OF THE
MONKEYS

It is to be hoped that the growing recognition of the worth
of comparative and genetic studies will lead to investiga-
tions of the mental make-up of other species of monkeys, and
to the careful overhauling of the work done so far, including
these rather fragmentary studies of mine. Work with three
monkeys of one species, especially when no general body of
phenomena, such as one has at hand in the case of domestic
animals, can be used as a means of comparison, must neces-
sarily be of limited application in all its details and of inse-
cure application even.in its general features. What I shall
say concerning the advance in the mental development
of the monkeys over that of other mammals may then be
in strictness true of only my three subjects, and it may be
left to the judgment of individuals to extend my conclusions

The Mental Life of the Monkeys 237

as far as seems to them likely. To me it seems fairly likely
that the very general mental traits which the research has
demonstrated hold true with little variation in the monkeys
in general.

The monkeys represent progress in mental development
from the generalized mammalian type toward man : —

1. In their sensory equipment, in the presence of focalized
vision.

2. In their motor equipment, in the codrdinated move-
ments of the hand and the eye.

3. In their instincts or inherited nervous connections, in
their general physical and mental activity.

4. In their method of learning or associative processes ;
in —

Quicker formation of associations,
Greater number of associations,
Greater delicacy of associations,
Greater complexity of associations,
e. Greater permanence of associations.

The fact of (1) is well known to comparative anatomists.
Its importance in mental development is perhaps not real-
ized, but appears constantly to a systematic student.

(2) is what accounts for much of the specious appearance
of human ways of thinking in the monkeys and becomes in
its human extension the handy tool for much of our intel-
lectual life. It is in great measure the prerequisite of 4c.

(3) accounts for the rest of such specious appearances, is
at the basis of much of 4 0, presages the similar though
extended instincts of the human being, which I believe are
the leading efficient causes of human mental capacity, and
is thus the great mental bond which would justify the in-
clusion of monkeys and man in a common group if we were
to classify animals on the basis of mental characteristics.

SS Ste

238 Animal Intelligence

Even the casual observer, if he has any psychological in-
sight, will be struck by the general, aimless, intrinsically
valuable (to the animal’s feelings) physical activities of a
monkey compared with the specialized, definitely aroused,
utilitarian activities of a dog or cat. Watch the latter and
he does but few things, does them in response to obvious
sense presentations, does them with practical consequences
of food, sex-indulgence, preparation for adult battles, etc.
If nothing that appeals to his special organization comes
up, he does nothing. Watch a monkey and you cannot
enumerate the things he does, cannot discover the stimuli
to which he reacts, cannot conceive the raison déire of
his pursuits. Everything appeals to him. He likes to be
active for the sake of activity.

The observer who has proper opportunities and takes
proper pains will find this intrinsic interest to hold of men-
tal activity as well. No. 1 happened to hit a projecting
wire so as to make it vibrate. He repeated this act hun-
dreds of times in the few days following. He did not, could
not, eat, make love to, or get preliminary practice for the
serious battles of life out of, that sound. But it did give
him mental food, mental exercise. Monkeys seem to enjoy
strange places; they revel, if I may be permitted an an-
thropomorphism, in novel objects. They like to have
feelings as they do to make movements. The fact of men-
tal life is to them its own reward.

It is beyond question rash for any one to venture hy-
potheses concerning the brain parallel of mental conditions,
most of all for the ignoramus in the comparative histology
of the nervous system, but one cannot help thinking that
the behavior of the monkeys points to a cerebrum that is no
longer a conservative machine for making a few well-defined
sorts of connections between sense-impressions and acts,

The Mental Life of the Monkeys 239

that is not only fitted to do more delicate work in parts,
but is also alive, tender all over, functioning throughout,
set off in action by anything and everything. And if one
adds coérdinations allowing a freedom and a differentiation
of action of the muscles used in speech comparable to that
already present in connection with the monkey’s hand, he
may well ask, ““What more of a nervous mechanism do
you need to parallel the behavior of the year-old child?”
However, this is not the place to speculate upon the impor-
tance to human development of our instinctive aimless
activity, physical and mental, or to describe further its
similarity and evident phylogenetic relationship to the in-
stinctive behavior of the monkeys. Elsewhere I shall under-
take that task.

4. In their method of learning, the monkeys do not ad-
vance far beyond the generalized mammalian type, but in
their proficiency in that method they do. They seem at
least to form associations very much faster, and they form
very many more. They also seem superior in the delicacy
and in the complexity of the associations formed and the
connections seem to be more permanent.

This progress may seem, and doubtless will to the thinker
who looks upon the human intellect as a collection of func-
tions of which ideation, judgment and reasoning are chief,
to be slight. To my mind it is not so in reality. For it
seems to me highly probable that the so-called ‘ higher’ in-
tellectual processes of human beings are but secondary re-
sults of the general function of having free ideas and that
this general function is the result of the formation after the
fashion of the animals of a very great number of associations.
I should therefore say, ‘““Let us not wonder at the com-
parative absence of free ideas in the monkeys, much less at
the absence of inferences or concepts. Let us not wonder

240 Animal Intelligence

that the only demonstrable intellectual advance of the mon-
keys over the mammals in general is the change from a few,
narrowly confined, practical associations to a multitude of
all sorts, for that may turn out to be at the bottom the
only demonstrable advance of man, an advance which in con-
nection with a brain acting with increased delicacy and
irritability, brings in its train the functions which mark off
human mental faculty from that of all other animals.

The typical process of association described in Chapter IT
has since been found to exist among reptiles (by Mr. R.
M. Yerkes) and among fishes (by myself). It seems fairly
likely that not much more characterizes the primates. If
such work as that of Lubbock and the Peckhams holds its
own against the critical studies of Bethe, this same process
exists in the insects. Yerkes and Bosworth think they
have demonstrated its presence in the crayfish. Even if
we regard the learning of the invertebrates as problematic,
still this process is the most comprehensive and important
thing in mental life. I have already hinted that we ought
to turn our views of human psychology upside down and
study what is now casually referred to in a chapter on habit
or on the development of the will, as the general psycho-
logical law, of which the commonly named processes are
derivatives. When this is done, we shall not only relieve
human mentality from its isolation and see its real rela-
tionships with other forms; we may also come to know more
about it, may even elevate our psychologies to the explana-
tory level and connect mental processes with nervous activ-
ities without arousing a sneer from the logician or a grin
from the neurologist.

CHAPTER VI

LAWS AND HYPOTHESES FOR BEHAVIOR

LAWS OF BEHAVIOR IN GENERAL

Behavior is predictable. The first law of behavior, one
fraction of the general law of the uniformity of nature, is
that with life and mind, as with mass and motion, the same
cause will produce the same effect, — that the same situa-
tion will, in the same ammal, produce the same response, —
and that if the same situation produces on two occasions two
different responses, the animal must have changed.

Scientific students of behavior will, with few exceptions,
accept this law in theory, but in practice we have not fully
used it. We have too often been content to say that aman
may respond in any one of several ways to the same situa-
tion, or may attend to one rather than another feature of
the same object, without insisting that the man must in each
case be different, and without searching for the differences
in him which cause the different reactions.

The changes in an organism which make it respond differ-
ently on different occasions to the same situation range from
temporary to permanent changes. Hunger, fatigue, sleep,
and certain diseases on the one hand, and learning, immu-
nity, growth and senility on the other, illustrate this range.

Behavior is predictable without recourse to magical agen-
cies. It is, of course, the case that any given difference
between the responses of an animal+to the same situation

R 241

242 Animal Intelligence

depends upon some particular difference in the animal. Each
immunity, for example, has its detailed representation in an
altered condition of the blood or other bodily tissue. In
general the changes in an animal which cause changes in its
behavior to the same situation are fully enumerated in a
list of the bodily changes concerned. That is, whatever
changes may be supposed to have taken place in the animal’s
vital force, spiritual essence, or other magical bases for life
and thought, are useless for scientific explanation and con-
trol of behavior.

No competent thinker probably doubts this in the case of
such changes as are referred to by hunger, sleep, fatigue, so-
called ‘functional’ diseases and immunity, and those who do
doubt it in the case of mental growth and learning seem to
represent an incomplete evolution from supernatural, or
rather infrascientific, thinking. There may be in behavior
a surplus beyond what would be predictable if the entire
history of every atom in the body was known — a surplus
necessarily attributable to changes in the animal’s incor-
poreal structure. But scientific thinkers properly refuse
to deliberately count upon such a surplus.

Every response or change in response of an animal is then
the result of the interaction of tts original knowable nature and
the environment. This may seem too self-evident a corollary
for mention. It should beso, but, unfortunately, it is not.
Two popular psychological doctrines exist in defiance of it.
One is the doctrine that the movements of early infancy are
random, the original nature of the animal being entirely
indifferent as to what movement shall be made upon a given
stimulus. But no animal can have an original nature that
does not absolutely prescribe just what the response shall
be to every stimulus. If the movements are really random,
they occur by virtue of some force that works at random.

Laws and Hypotheses for Behavior 243

If the movements are really the result of the action of the en- |

vironment on the animal’s nature, they are never random. |

A baby twiddles his thumbs or waves his legs for exactly the |
same sort of reason that a chick pecks at a worm or preens |

its wing.

The other doctrine which witnesses to neglect of the
axiom that behavior is the creation of the environment, act-
ing on the animal’s nature, is the doctrine that the need
for a certain behavior helps to create it, that being in a
difficulty tends in and of itself to make an animal respond so
as to end the difficulty.

The truth is that to a difficulty the animal responds by
whatever its inherited and acquired nature has connected
with the special form of difficulty and that in many animals
the one response of those thus provided which relieves the
difficulty is selected and connected more firmly with that
difficulty’s next appearance. The difficulty acts only as a
stimulus to the animal’s nature and its relief acts only as a

premium to the connection whereby it was relieved. The |

2?

law of original behavior, or the law of instinct, is then that _

to any situation an animal will, apart from learning, respond |

j

by virtue of the inherited nature of its reception-, connection- —

and action-systems.

The inquiry into the laws of learning to be made in this
essay is limited to those aspects of behavior which the term
has come historically to signify, that is, to intellect, skill,
morals and the like.

For the purposes of this essay it is not necessary to decide
just what features of an animal’s behavior to include under
intellect, skill, morals and the like. The statements to be
made will fit any reasonable dividing line between behavior
on the one side and mere circulation, digestion, excretion
and the like on the other. There should in fact be no clear

244 Animal Intelligence

dividing line, since there is no clear gap between those
activities which naturalists have come to call behavior and
the others.

The discussion will include: First, a description of two
laws of learning; second, an argument to prove that no ad-
ditional forces are needed — that these two laws explain all
learning; and third, an investigation of whether these two
laws are reducible to more fundamental laws. I shall also
note briefly the consequences of the acceptance of these laws
in one sample case, that of the study of mental evolution.

PROVISIONAL LAWS OF ACQUIRED BEHAVIOR OR
LEARNING

The Law of Effect is that: Of several responses made to
the same situation, those which are accompanied or closely
followed by satisfaction to the animal will, other things being
equal, be more firmly connected with the situation, so that,
when it recurs, they will be more likely to recur; those which
are accompamed or closely followed by discomfort to the ami-
mal will, other things being equal, have their connections with
that situation weakened, so that, when it recurs, they will be
less likely to occur. The greater the satisfaction or discomfort,
the greater the strengthening or weakening of the bond.

The Law of Exercise is that: Any response to a situation
will, other things being equal, be more strongly connected with
the situation in proportion to the number of times it has been
connected with that situation and to the average vigor and dura-
tion of the connections.

These two laws stand out clearly in every series of ex-
periments on animal learning and in the entire history of the
management of human affairs. They give an account of
learning that is satisfactory over a wide range of experience,

Laws and Hypotheses for Behavior 245

so long as all that is demanded is a rough and general means
of prophecy. We can, as a rule, get an animal to learn a
given accomplishment by getting him to accomplish it,
rewarding him when he does, and punishing him when he
does not; or, if reward or punishment are kept indifferent,
by getting him to accomplish it much oftener than he does
any other response to the situation in question.

For more detailed and perfect prophecy, the phrases
‘result in satisfaction’ and ‘result in discomfort’ need fur-
ther definition, and the other things that are to be equal need
comment.

By a satisfying state of affairs is meant one which the
animal does nothing to avoid, often doing such things as
attain and preserve it. By a discomforting or annoying
state of affairs is meant one which the animal commonly
avoids and abandons.

The satisfiers for any animal in any given condition can-
not be determined with precision and surety save by obser-
vation. Food when hungry, society when lonesome, sleep
when fatigued, relief from pain, are samples of the common
occurrence that what favors the life of the species satisfies
its individual members. But this does not furnish a com-
pletely valid rule.

The satisfying and annoying are not synonymous with
favorable and unfavorable to the life of either the individual
or the species. Many animals are satisfied by deleterious
conditions. Excitement, overeating, and alcoholic intoxi-
cation are, for instance, three very common and very potent
satisfiers of man. Conditions useful to the life of the species
in moderation are often satisfying far beyond their useful
point: many conditions of great utility to the life of the
species do not satisfy and may even annoy its members.

The annoyers for any animal follow the rough rule that

246 Animal Intelligence

alterations of the animal’s ‘natural’ or ‘normal’ structure —
as by cuts, bruises, blows, and the like, — and deprivations
of or interference with its ‘natural’ or ‘normal’ activities, —
as by capture, starvation, solitude, or indigestion, — are in-
tolerable. But interference with the structure and func-
tions by which the species is perpetuated is not a sufficient
criterion for discomfort. Nature’s adaptations are too
crude.

Upon examination it appears that the pernicious states of
affairs which an animal welcomes are not pernicious at the
time, to the neurones. We learn many bad habits, such as
morphinism, because there is incomplete adaptation of all
the interests of the body-state to the temporary interest of
its ruling class, the neurones. So also the unsatisfying
goods are not goods to the neurones at the time. Weneglect
many benefits because the neurones choose their immediate
advantage. The neurones must be tricked into permitting
the animal to take exercise when freezing or quinine when
in a fever, or to free the stomach from certain poisons.

Satisfaction and discomfort, welcoming and avoiding, thus
seem to be related to the maintenance and hindrance of the
life processes of the neurones rather than of the animal as a
whole, and to temporary rather than permanent mainte-
nance and hindrance.

The chief life processes of a neurone concerned in learning
are absorption of food, excretion of waste, reception and
conduction of the nerve impulse, and modifiability or change
of connections. Of these only the latter demands comment.

The connections formed between situation and response
are represented by connections between neurones and neu-
rones, whereby the disturbance or neural current arising in
the former is conducted to the latter across their synapses.
The strength or weakness of a connection means the greater

Laws and Hypotheses for Behavior 247

or less likelihood that the same current will be conducted
from the former to the latter rather than to some other place.
The strength or weakness of the connection is a condition
of the synapse. What condition of the synapse it is remains
a matter for hypothesis. Close connection might mean pro-
toplasmic union, or proximity of the neurones in space, or a
greater permeability of a membrane, or a lowered electrical
resistance, or a favorable chemical condition of some other
sort. Let us call this undefined condition which parallels
the strength of a connection between situation and response
the intimacy of the synapse. Then the modifability or
connection changing of a neurone equals its power to alter
the intimacy of its synapses.

As a provisional hypothesis to account for what satisfies
and what annoys an animal, I suggest the following : —

A neurone modifies the intimacy of its synapses so as to
keep intimate those by whose intimacy its other life pro-
cesses are favored and to weaken the intimacy of those
whereby its other life processes are hindered. The animal’s
action-system as a whole consequently does nothing to avoid
that response whereby the life processes of the neurones
other than connection-changing are maintained, but does
cease those responses whereby such life processes of the
neurones are hindered.

This hypothesis has two important consequences. First:
Learning by the law of effect is then more fully adaptive for
the neurones in the changing intimacy of whose synapses
learning consists, than for the animal as a whole. It is
adaptive for the animal as a whole only in so far as his or-
ganization makes the neurones concerned in the learning
welcome states of affairs that are favorable to his life and
that of his species and reject those that are harmful.

Second: A mechanism in the neurones gives results in

248 Animal Intelligence

the behavior of the animal as a whole that seem beyond
mechanism. By their unmodifiable abandonment of certain
specific conditions and retention of others, the animal as a
whole can modify its behavior. Their one rule of conduct
causes in him a countless complexity of habits. The learn-
ing of an animal is an instinct of its neurones.

I have limited the discussion to animals in whom the con-
nection-system is a differentiated organ, the neurones. In
so far as the law of effect operates in an animal whose con-
nection-system is not anatomically distinguishable and is
favored and hindered in its life by the same conditions that
favor and hinder the life of the animal as a whole, the satis-
fying and annoying will be those states of affairs which the
connection-system, whatever it be, maintains and abandons.

The other things that have to be equal in the case of the
law of effect are: First, the frequency, energy and dura-
tion of the connection, — that is, the action of the law of ex-
ercise; second, the closeness with which the satisfaction is
associated with the response; and, third, the readiness of the
response to be connected with the situation.

The first of these accessory conditions requires no com-
ment. A slightly satisfying or indifferent response made
often may win a closer connection than a more satisfying
response made only rarely.

The second is most clearly seen in the effect of increasing
the interval between the response and the satisfaction
or discomfort. Such an increase diminishes the rate of
learning. If, for example, four boxes were arranged so that
turning a button caused a door to open (and permit a cat
to get freedom and food) in one, five, fifty and five hundred
seconds, respectively, a cat would form the habit of prompt
escape from the first box most rapidly and would almost
certainly never form that habit in the case of the fourth.

Laws and Hypotheses for Behavior 249

The electric shock administered just as an animal starts on
the wrong path or touches the wrong mechanism, is potent,
but the same punishment administered ten or twenty
seconds after an act will have little or no effect upon that
act.

Close temporal sequence is not the only means of insuring
the connection of the satisfaction with the response producing
it. What is called attention to the response counts also.
If a cat pushes a button around with its nose, while its main
occupation, the act to which its general ‘set’ impels it, to
which, we say, it is chiefly attentive, is that of clawing at
an opening, it will be less aided in the formation of the habit
than if it had been chiefly concerned in what its nose was
doing. The successful response is as a rule only a part of all
that the animal is doing at the time. In proportion as it |
is an eminent, emphatic part of it, learning is aided. Sim-
ilarly discomfort eliminates most the eminent, emphatic
features of the total response which it accompanies or
shortly follows.

The third factor, the susceptibility of the response and
situation to connection, is harder to illustrate. But, ap-
parently, of those responses which are equally strongly con-
nected with a situation by nature and equally attended to,
some are more susceptible than others to a more intimate
connection.

The things which have to be equal in the case of the law
of exercise are the force of satisfyingness; that is, the
action of the law of effect, and again the readiness of
the response to be connected with the situation.

The operation of the laws of instinct, exercise and effect
is conditioned further by (1) what may be called the law
of assimilation or analogy, — that a situation, especially
one to which no particular response is connected by original

250 Animal Intelligence

nature or previous experience, may connect with whatever
response is bound to some situation much like it, — and (2)
by the law of partial activity —that more or less of the
total situation may be specially active in determining the
response.

The first of these laws is a result of the facts that conduc-
tion in the neurones follows the line of least resistance or
closest connection, that the action-system is so organized
that certain responses tend to be made in their totality if
at all, and that slightly different situations may, therefore,
produce some one response, the effects of their differences
being in the accessories of that response.

The second law is a result of the facts that the situation,
itself a compound, produces a compound action in the neu-
rones, and that by reason of inner conditions, the relative
intensities of different parts of the compound may vary.
The commonest response will be that due to the modal
condition of the neural compound, but every condition
of the compound will have its response.

THE ADEQUACY OF THE LAWS OF EXERCISE AND
EFFECT

Behavior has been supposed to be modified in accordance
with three other principles or laws besides the law of exercise
and the law of effect. Imitation is often used as a name
for the supposed law that the perception of a certain re-
sponse to a situation by another animal tends in and of it-
self to connect that response to that situation. Common
acceptance has been given to more or less of the law that
the idea of an act, or of the result of an act, or of the im-
mediate or remote sensations produced by the act, tends
in and of itself to produce the act. Such a law of ‘sugges-

Laws and Hypotheses for Behavior 251

tion’ or ‘ideo-motor’ action may be phrased differently,
but in whatever form, it insists that the bond between a
situation and some conscious representation of a response
or of its consequences can do the work of the bond between
the situation and the response itself. In acts of reasoning
man has been supposed to connect with a given situation a
response that could never have been predicted merely from
knowledge of what responses were connected with that
situation by his original nature or had been connected with
it by the laws of exercise and effect. Inference has been
supposed to create bonds in and of itself and to be above
the mere laws of habit.

Various forms of statement, most of them vague, have
been and would be used in describing the potency of a per-
ceived response, a thought-of response, or a train of infer-
ence, to produce a response and bind it to the given total
situation. Any forms will do for the present argument,
since all forms mean to assert that responses can be and
often are bound to situations otherwise than by original
bodily nature, satisfaction, discomfort, disuse and use. I
shall try to show that they cannot; ‘that, on the contrary,
the laws of exercise and effect account for all learning.

The facts of imitation in human and animal behavior are
explainable by the laws of instinct, exercise and effect.

Some cases of imitation are undoubtedly mere instincts
in which the situation responded to is an act by another of
the same species. If the baby smiles at a smile, it is be-
cause of a special, inborn connection between that sight
and that act, — he smiles at a smile for just the same rea-
son that he draws down his mouth and wails at harsh
words. At that stage of his life he does not imitate other
simple acts. A man runs with a crowd for the same reason
that he runs from a tiger. Returning a blow is no more due
to a general tendency to imitate than warding it off is.

252 Animal Intelligence

Other cases of imitation are mere adjuncts to the ordinary
process of habit-formation. In the first place, the act of an-
other, or its result, may serve as a model by which the satis-
fyingness of one’s own responses are determined. Just as
the touch and taste of food tells a baby that he has got it
safely into his mouth, so the sound of a word spoken by an-
other or the sight of another performing some act of skill
tells us whether our pronunciation or technique is right or
wrong.

In the second place, the perception of another’s act may
serve as a stimulus to a response whereby the situation is
altered into one to which the animal responds from habit by
an act like the one perceived. For example, the perception
of another making a certain response (A) to a situation (B)
may lead in me by the laws of habit to a response (C)
which puts me in a situation (D) such that the response (A)
is made by me by the laws of habit. Suppose that by pre-
vious training the act of taking off my hat (A) has become
connected as response to the situation (D), ‘ thought of hat
off,’ and suppose that with the sight of others uncovering
their heads (A) in church (B) there has, again by previous
habituation, been connected, as response (C), ‘thought of
hat off.’ Then the sight of others uncovering their heads
would by virtue of the laws of habit lead me to uncover.
Imitation of this sort, where the perception of the act or
condition in another gives rise to the idea of performing the
act or attaining the condition, the idea in turn giving rise
to the appropriate act, is certainly very common.

There may be cases of imitation which cannot be thus
accounted for as special instinctive responses to the percep-
tion of certain acts by the same acts, as habits formed under
the condition that the satisfyingness of a response is its
likeness to the perceived act of another, or as the connection

Laws and Hypotheses for Behavior 253

of two habits, one of getting, from the perceived act of an-
other, a certain inner condition, the other of getting, from
this inner condition, the act in question. There may be,
that is, cases where the perceived act of another in and of
itself creates a connection.

It is apparently taken for granted by a majority of writ-
ers on human behavior that cases of such direct mental in-
fection, as it were, not only exist, but are the rule. I am
unable to find proof of such cases, however. Those com-
monly quoted are far from clear. Learning to talk in the
human infant, for example, the stock case of imitation as a
direct means of learning, offers only very weak and du-
bious evidence. Since what is true of it holds substan-
tially for the other favored cases for learning by imitation, I
shall examine it at some length.

Let us first be clear as to the alternative explanations of
linguistic imitation. The first is that seeing the movements
of another’s mouth-parts or hearing a series of word-sounds
in and of itself produces the response of making that series
of sounds or one like it.

The other is that the laws of instinct and habit are ade-
quate to explain the fact in the following manner: A
child instinctively produces a great variety of sounds and
sound-series. Some of these, accepted as equal to words by
the child’s companions, are rewarded, so that the child
learns by the law of effect to use them in certain situations to
attain certain results. It is possible also that a child in-
stinctively feels a special satisfaction at babbling when
spoken to and a special satisfaction at finding the sound he
makes like one that rings in the ears of memory and has
meaning. The latter would be like the instinctive satisfac-
tion apparently felt in constructing an object which is like
some real object whose appearance and meaning he knows.

254 Animal Intelligence

A child also meets frequently the situations ‘say dada,’
‘say mama,’ ‘say good night’ and the like,! and is rewarded
when his general babble produces something like the word
spoken to him. He thus, by the law of effect, learns to re-
spond to any ‘say’ situation by making some sound and to
each of many ‘say’ situations by making an appropriate
sound, and to feel satisfaction at duplicating these words
when heard. According to the amount of such training,
the tendency to respond to words spoken to him by mak-
ing some sound may become very strong, and the number
of successful duplications very large. Satisfaction may be
so connected with saying words that the child practices
them by himself orally and even in inner speech. ‘The sec-
ond alternative relies upon the instinct of babbling, and the
satisfaction of getting desirable effects from speech, either
the effect which the word has by its meaning as a request
(‘water,’ ‘milk,’ ‘take me outdoors’ and the like) or the
effect which it has by its mere sound upon companions
who notice, pet or otherwise reward a child for linguistic
progress.

There are many difficulties in the way of accepting the
first alternative. First of all, no one can believe that all
of a child’s speech is acquired by direct imitation. On
many occasions the process is undoubtedly one of the pro-
duction of many sounds, irrespective of the model given, and
the selection of the best one by parental reward. Any stu-
dent who will try to get a child who is just beginning to
speak, to say cat, dog and mouse and will record the
sounds actually made by the child in the three cases, will
find them very much alike. There will in fact be little

1The ‘say,’ may be replaced by some bodily attitude, facial expression,
or other verbal formula that identifies the situation as one to be responded
to by speech.

Laws and Hypotheses for Behavior 255

that even looks like direct imitation until the child has
‘learned’ at least forty or fifty words.

The second difficulty lies in the fact that different chil-
dren, in even the clearest cases of the imitation of one
sound, vary from it in so many directions. A list of all the
sounds made in response to one sound heard is more sug-
gestive of random babble as modified by various habits of
duplicating sounds, than of a direct potency of the model.
Ten children of the same age may, in response to ‘ Christ-
mas,’ say, kiss, kissus, krismus, mus, kim, kimus, kiruss,
i-us and even totally unlike vocables such as hi-yi or ya-ya.

The third difficulty is that in those features of word-
sounds which are hard to acquire, such as the ‘th’ sound,
direct imitation is inadequate. ‘The teacher has recourse to
trial and chance success, the spoken word serving as a model
to guide satisfaction and discomfort. In general no sound
not included in the instinctive babble of children seems to be
acquired by merely hearing and seeing it made.

A fourth difficulty is that by the doctrine of direct imi-
tation it should not be very much more than two or three
times as hard to repeat a two- or three-syllable series as to
repeat a single syllable. It is, in fact, enormously harder.
This is, of course, just what is to be expected if learning a
sound means the selection from random babbling plus pre-
vious habits. If, for instance, a child makes thirty mono-
syllabic sounds like pa, ga, ta, ma, pi, gi, li, mi, etc., there
is, by chance, one chance in thirty that in response to a
word or phrase he will make that one-syllable sound of his
repertory which is most like it, but there is only one chance
in nine hundred that he will make that two-syllable combina-
tion of his repertory which is most like it.

On the other hand, two objections will be made to the op-
posite view that the word spoken acts only as a model to

250 Animal Intelligence

select from responses otherwise caused, or as a stimulus to
habits already existing. First it will be said that clear, in-
dubitable repetitions of words never practiced by the child,
either as totals or in their syllables separately, do occur, —
that children do respond by repeating a word in cases where
full knowledge of all their previous habits would give no
reason to expect them to make such a connection. To this
the only retort is that such observations should be based on
a very delicate and very elaborate record of a child’s linguis-
tic history, and that until they are so made, it is wise to
withhold acceptance.

The second objection is that the rapid acquisition of a
vocabulary such as occurs in the second and third year is
too great a task to be accomplished by the laws of exercise
and effect alone. This objection is based on an overestima-
tion of the variety of sounds which children of the ages in
question make. For example, a child who says 250 words,
including say 400 syllables, comprising say 300 syllables
which, when properly pronounced, are distinguishable, may
actually use less than 50 distinguishable syllables. Ba, may
stand for the first syllable of father, water, barn, park and
the like. Kz may stand for cry, climb, and even carry.
For a child to say a word commonly means that he makes
a sound which his intimate companions can recognize as his
version of that word. A child who can produce something
like each one of a thousand words upon hearing them, may
do so from actual control over less than a hundred sylla-
bles. If we suppose him to have acquired the habits,
first, of saying something in such a case, second, of respond-
ing to a certain hundred sounds when perceived or re-
membered by making, in each case, a similar sound, and,
third, of responding to any other sound when perceived or
remembered, by making that sound of his own repertory

Laws and Hypotheses for Behavior 257

which is most like it, we can account for a thousand ‘imita-
tions,’ and still not have made a large demand upon childish
powers of learning.

No one should pretend to have disproved direct imitation
in the case of learning to talk until he has subjected all these
and other matters to crucial experiments. But the burden
of proof does seem to belong upon those who deny the ade-
quacy of the laws of exercise and effect. In so far as the
choice is between accepting or rejecting a general law that,
other things being equal, the perception of a response in
another produces that response, we surely must reject it.
Some of the cases of imitation may be unexplained by the
laws of exercise and effect. But for others no law of imita-
tion is required. And of what should happen by such a law
not over a trivial fraction at most does happen.

The idea of a response is in and of itself unable to produce
that res ponse.

The early students of behavior, considering human be-
havior and emphasizing behavior that was thought about
and purposive, agreed that the sure way to connect a re-
sponse with a situation was to choose, or will, or consent to,
that response. Later students still agreed that to think
about the response in some way, to have an image of it or of
the sensations caused in you by previous performances of it,
was a strong provocative to it. To get a response, get some
sort of conscious representative of it, has been an acceptable
maxim. Medicine, education and even advertising have
based their practice upon the theory that ideas tended to
issue in the particular sort of acts that they were ideas of.

The laws of exercise and effect, on the contrary, if they

1 This would, of course, result from a well-known corollary of the laws of

habit.
8

258 Animal Intelligence

are the sole laws of modifiability, insist that the thought of
an act will produce that act only if the act has been con-
nected with that thought (and without resulting discomfort)
in the animal’s past.

It seems plausible that there should be a peculiar bond
between the thought of a response and the response. The
plausibility is due to two reasons, one of which is sound but
inadequate, the other being, in my opinion, entirely un-
sound. The first reason is that, as a mere matter of fact,
the thought of a response does so often produce it. The
second is that an idea of a response seems a natural and
sufficient cause for it to appear. The first reason is inade-
quate to justify any law of the production of a response by
its image or other representative, since evidence can be
found to show that when a response is produced by an idea
of it, it has been already bound to that idea by repetition or
satisfaction. ‘The second reason is unsound because, even
if responses are brought to pass occasionally by their
images, that is surely an extremely rare and unnatural
method.

It is certain that in at least nine cases out of ten a re-
sponse is produced, not by an image or other representation
of it, but by a situation nowise like it or any of its accesso-
ries. Hunger and the perception of edible objects, far out-
weigh ideas of grasping, biting and swallowing, as causes
of the eating done in the world. Objects sensed, not im-
ages of eye-movements, cause a similar overwhelming ma-
jority of the eye’s responses. We walk, reach and grasp
on most occasions, not because of anticipatory images of
how it will feel to do so or verbal descriptions to ourselves
of what we are to do, but because we are stimulated by the
perception of some object.

It is also certain that the idea of a response may be im-

Laws and Hypotheses for Behavior 259

potent to produce it. I cannot produce a sneeze by think-
ing of sneezing. A child may have, in the case of some
simple bodily act, which he has done in response to certain
situations thousands of times, as adequate ideas of it as are
possessed by others, and yet be utterly unable to make him-
self do it; many adults show this same phenomenon, for
instance, in the case of swallowing a pill. And, of course,
one can have ideas of running a mile in two minutes, jump-
ing a fence eight feet high, or drawing a line exactly equal
to a hundred millimeter line, just as easily as of running the
mile in ten minutes, or jumping four feet.

It is further certain that the thought of doing one thing
very often results in the man’s doing something quite dif-
ferent. The thought of moving the eyes smoothly without
stops along a line of print has occurred to many people, who
nevertheless actually did as a result move the eyes in a series
of jumps with long stops.

It is further certain that in many cases where an animal
does connect a given response with the image or thought of
that response, the connection has been built up by the laws
of exercise and effect. Such cases as appropriate responses
to, ‘I will go to bed,’ ‘I will get up,’ ‘I will eat,’ ‘I will write
a letter,’ ‘I will read,’ or to the corresponding commands,
requests or suggestions, are observably built up by training.
The appropriate response follows the idea only if it has,
by repetition or reward, been connected with it or something
like it. If the only requirement in moral education were to
have the idea of the right act at the right time, the lives of
teachers and parents would be greatly alleviated. But the
decision to get up, or the idea of getting up or of being up,
is futile until the child has connected therewith the actual
act of getting up.

The defender of the direct potency of conscious represent-

260 Animal Intelligence

atives of a response to produce it may be tempted to com-
plain at this point that what the laws of exercise and effect
do is to reduce the strength of competing ideas, and leave the
idea, say of getting up, free to exercise its direct potency.
The complaint shows a weak sense for fact. The ordinary
child is not a Hamlet, nor is he beguiled by the imagined
delights of staying in bed, nor repelled by the image of get-
ting up out of it. On thecontrary, he may be entirely will-
ing to think of getting up. It is the actual delights that
hold him, the actual discomforts that check him, and the
only way to be sure that he will get up is so to arrange mat-
ters that it is more satisfactory to him to get up than not to
when the situation, whatever it be, that is to suggest that
response, makes its appearance.

The experience of every schoolroom shows that it is not
enough to get the idea of an act. The act must have gone
with that idea or be now put with it. The bond must be
created. Responses to the suggestions of language, whether
addressed to us by others or by ourselves in inner speech,
in a very large majority of cases owe their bonds to the laws
of exercise and effect. We learn to do what we are told,
or what we tell ourselves, by doing something and rejecting
or retaining what we do by virtue of its effects. So also in
the case of a majority of responses to the suggestions of other
than verbal imagery.

The idea of a response, like the perception of a response
by another, acts often as a guide to response ex post facto by
deciding what shall be satisfying. Where superficial inspec-
tion leaves the impression that the idea creates the act, a
little care often shows it to have only selected from the acts
produced by instinct and habit. For example, let the reader
think of some act never performed hitherto, such as putting
his left middle finger upon the upper right hand corner of

Laws and Hypotheses for Behavior 261

this page, and make the movement. It may seem at first
sight that having the idea entirely unopposed was the suffi-
cient cause of the act. But careful experiment, including,
for instance, the closure of the eyes and anesthesia of the
fingers will reveal that the original propulsion of the idea is
not to just that act, but to many possibilities, and that its
chief potency lies in the fact that not to get the finger to
that point is annoying, and that consequently the organism
is at peace only when the act is done.

So far it has been shown that: The majority of responses
are not produced by ideas of them. The idea of a response
may be impotent to produce it. The idea of one act may
produce a different, even an opposite act. When an idea
seems to produce a response in and of itself, it may really act
by determining the satisfyingness of responses otherwise
made. These facts are sufficient to destroy the pretensions
of any general law that the image of an act will, other things
being equal, produce it. But the possibility that such an
image may occasionally exercise this peculiar potency re-
mains.

I despair of convincing the reader that it does not. Man
is the only animal possessing a large fund of ideas of acts,
and man’s connection-system is so complex and his ideas of
acts are so intricately bound to situations that have by
use and effect produced those acts, that the proof of this
negative is a practical impossibility. But it is possible to
show that even the most favored cases for the production
of a response by securing an ideal representation of it may
be explainable by use and effect alone.

The extreme apparent potency of ideas representing acts
to produce them regardless of bonds of use or effect is, of
course, witnessed in the phenomena of suggestion in hyp-
nosis and allied states. To try to reduce these phenomena

262 Animal Intelligence

to consequences of the laws of habit may seem fanatical.
Here, it will be said, are the crucial cases where the idea of
an act, if freed from all effects of opposing ideas, does in-
evitably produce the act so far as it is a possibility for the
animal’s action-system.

That is precisely what I cannot find proof of.

Efficient suggestions to hypnotized subjects, on the con-
trary, are often ambiguous in the sense that they seem as
likely to arouse a situation to which the act has been bound
by the law of habit as to arouse an idea of the act. Often
they are far better suited to the former purpose. Direct
commands — Walk, Dance, Get up, Sit down — obviously
will operate by the law of habit provided the situations
connected with disobedience are excluded. This is also
the case with such indirect suggestions as ‘This is a knife
(stick).’? ‘This is your sword (broom).’ ‘Have a cigar
(a pen).’

The release of a suggestion from inhibitions may as well
be the release from ideas connected as antecedents with not
performing the act as the release from zdeas of not perform-
ing it. It is a question of fact whether, to get an act done
by the subject, one must arouse in him an idea to which or
to a part of which or to something like which the act has been
bound by use or effect, or may arouse simply an idea of the
act.

Finally, if an idea has a tendency to connect with a cer-
tain response, over and above the bonds due to exercise and
effect, it should always manifest that tendency. If the
connection is not made, it must be due to the action of some
contrary force. It is less my duty to show that the laws of
habit can account for hypnotic suggestibility, obsessions,
and the like, than it is my opponents’ duty to explain why a
man can spend a half day in hospitably welcoming a hundred

Laws and Hypotheses for Behavior 263

ideas of acts and yet perform no one of them, save those in
the case of which he has learned to do the thing when he
thinks of doing it. Again, how can the mere addition of
the idea of a future date to the idea of an act so utterly
deprive it of present potency.

In view of ali these facts it seems probable that ideas of
responses act in connection just as do any other situations,
and that the phenomena of suggestion and ideo-motor
action really mean that any idea will, except for competing
ideas, produce the response, not that zs like it, but that has
gone with it, or with some idea like it.

Rational connections are, in their causation, like any
others, the difference being in what is connected.

It remains to ask whether situation and response are
bound together in the case of reasoning by any other forces
than the forces of repetition, energy and satisfaction? Do
the laws of inferential thinking transcend the laws of exer-
cise and effect? Or does the mind, even in these novel and
constructive responses, do only what it is forced to do by
original nature or has done without discomfort ?

To defend the second alternative involves the reduction
of the processes of abstraction, association by similarity and
selective thinking to mere secondary consequences of the
laws of exercise and effect. This I shall try to do.

The gist of the fact of abstraction is that response may be
made to some elements or aspects of a situation which have
never been experienced in isolation, and may be made to the
element in question regardless of the gross total situation in
which it inheres. A baby thus learns to respond to its
mother’s face regardless of what total visual field it is a part
of. A child thus learns to respond by picking out any red
object, regardless of whether the redness be in an apple, a

264 Animal Intelligence

block, a pencil, a ribbon or a ball. A student thus learns to
respond to any plane surface inclosed by three straight lines
regardless of its size, shape, color or other than geometrical
meaning.

What happens in such cases is that the response, by being
connected with many situations alike in the presence of the
element in question and different in other respects, is bound
firmly to that element and loosely to each of its concomitants.
Conversely any element is bound firmly to any one response
that is made to all situations containing it and very, very
loosely to each of those responses that are made to only a
few of the situations containing it. The element of triangu-
larity, for example, is bound firmly to the response of saying
or thinking ‘triangle’ but only very loosely to the response
of saying or thinking white, red, blue, large, small, iron, steel,
wood, paper and the like. A situation thus acquires bonds
not only with some response to it as a gross total, but also
with responses to each of its elements that has appeared in
any other gross totals.

Appropriate response to an element regardless of its con-
comitants is a necessary consequence of the laws of exercise
and effect if an animal learns to make that response to the
gross total situations that contain the element and not to
make it to those that donot. Such prepotent determination
of the response by one or another element of the situation
is no transcendental mystery, but, given the circumstances,
a general rule of all learning. The dog who responds ap-
propriately to ‘beg’ no matter when, where, or by whom
spoken, manifests the same laws of behavior. There is no
difficulty in understanding how each element of a situation
may come to tend to produce a response peculiar to it as
well as to play its part in determining the response to the
situation as a total. There may be some difficulty in under-

een,

Laws and Hypotheses for Behavior 265

standing how each element of a situation comes to be felt
whereas before only the gross total was felt. The change in
consciousness from the ‘big, blooming, buzzing confusion’
to an aggregate of well-defined percepts and images, which
accompanies the change in behavior from response to totals
to response to parts or elements, may be mysterious. With
the change in consciousness, however, we are not now con-
cerned. The behavior of man and other animals toward the
abstract elements of color, size, number, form, time or value
is explained by the laws of instinct, exercise and effect.

When the perception or thought of a fact arouses the
thought of some other fact identical in part with the for-
mer fact, we have so-called association by similarity. An
element of the neurone-action is prepotent in determining
the succeeding neurone-action. The particular way in
which it determines it is by itself continuing and making
connection with other associates. These it possesses by
virtue of the law of exercise and effect.

The changes in behavior classified under intellect and
morality seem then to be all explainable by the two laws
of exercise and effect. The facts of imitation really refer
to certain specific original connections or to the efficiency
of a model in determining what shall satisfy or to the pro-
vision of certain instructive situations in the form of the
behavior of other animals. The facts variously referred to
as suggestion, ideo-motor action or the motor power of ideas,
really refer to the fact, common in the human animal only,
that to those ideas that represent acts in thought the acts
are often bound as responses. The bonds are due to the
primary laws of effect and exercise. The facts of reason-
ing really refer to the fact of prepotency of one or another
element in a situation in determining the response.

266 Animal Intelligence

The reduction of all learning to making and rewarding
or avoiding and punishing connections between situation
and response allows changes in intellect and character to
be explained by changes in the neurones that are known
either to be or to be possible. I have elsewhere sketched
one such possible neural mechanism for the law of effect.?

On the contrary, imitation, suggestion and reasoning,
as commonly described, put an intolerable burden upon
the neurones. To any one who has tried to imagine a
possible action in the neurones to parallel the traditional
power of the mere perception of an act in another or of
the mere representation of an act as done by oneself to
produce that act, this is a great merit. For the only
adequate psychological parallel of traditional imitation
and suggestion would be the original existence or the gratui-
tous formation of a connection between (1) each neurone-
action corresponding to a percept of an act done by another
or to the idea of an act done by oneself and (2) the neurone-
action arousing that act. It is incredible that the neurone-
action corresponding to the perception of a response in
another, or to the idea of a response in oneself, or to the first
term in an association by similarity, should have, in and
of itself, a special power to determine that the next neurone-
action should be that paralleling the response in question.
And there is no possible physiological parallel of a power
to jump from premise to conclusion for no other reason
than the ideal fitness of the sequence.

SIMPLIFICATIONS OF THE LAWS OF EXERCISE AND EFFECT

There has been one notable attempt to’explain the facts
of learning by an even simpler theory than that represented

1In Essays Philosophical and Psychological in Honor of William James,
PP. 591-599.

Laws and Hypotheses for Behavior 267

in the laws of exercise and effect. Jennings has formulated
as an adequate account of learning the law that: “When
a certain physiological state has been resolved, through
the continued action of an external agent, or otherwise,
into a second physiological state, this resolution becomes
easier, so that in course of time it takes place quickly and
spontaneously ” (‘ Behavior of the Lower Organisms,’ p. 289).
“The law may be expressed briefly as follows: — The
resolution of one physiological state into another becomes
easier and more rapid after it has taken place a number of
times. ence the behavior primarily characteristic for
the second state comes to follow immediately upon the first
state. The operations of this law are, of course, seen on
a vast scale in higher organisms in the phenomena which
we commonly call memory, association, habit formation
and learning ” (ibid., p. 291). This law may be expressed
conveniently as a tendency of a series of states

A—~>B—->C->D
to become A~>D
or A>B!~?~C!'>D

B! and C! being states B and C passed rapidly and in a
modified way so that they do not result in a reaction but
are resolved directly into D.

If Professor Jennings had applied to this law the same
rigorous analysis which he has so successfully employed
elsewhere, he would have found that it could be potent
to cause learning only if supplemented by the law of effect
and then only for a fraction of learning.

For, the situations being the same, the state A cannot
produce, at one time, now B and, at another time, abbrevi-
ated, rudimentary B! instead of B. If A with S produces B
once, it must always. If D ora rudimentary B' is produced,
there must be something other than A; A must itself have

268 | Animal Intelligence

changed. Something must have been added to or sub-
tracted from it. In Professor Jennings’ own words, ‘‘Since
the external conditions have not changed, the animal it-
self must have changed ”’ (zbid., p. 286). And in adaptive
learning something related to the results of the S A con-
nection must have changed it.

The series A — B — C — D does not become the series
A—D or A— B!— C!—D by magic. If B and C are
weakened and D is strengthened as sequents of A in re-
sponse to S, it is because something other than repetition
acts upon them. Repetition alone could not blow hot
for D and cold for B.

Moreover, as a mere matter of fact, ‘‘the resolution of one
physiological state into another”? through intermediate
states does not with enough repetition ‘“‘become easier so
that in course of time it takes place quickly and spontane-
ously.”

Paramecium does not change its response to, say, an ob-
stacle in the water, from swimming backward, turning to
one side and swimming forward by abbreviating and even-
tually omitting the turn and the backward movement.
The schoolboy does not tend to count 1, 2, 10 or to say
a, b, z, or give ablative plurals after nominative singulars.

Repetition of a series of physiological states in and of it-
self on the contrary makes an animal increasingly more
likely to maintain the series in toto. It is hard to give the
first and then the last word of an oft repeated passage like
Hamlet’s soliloquy or the Lord’s Prayer, or to make readily
the first and then the last movement of writing a name or
address. Repetition never eliminates absolutely and elim-
inates relatively the Jess often or less emphatically connected.

Even if supplemented by the law of effect, so that some
force is at hand to change the effect of S upon the animal

Laws and Hypotheses for Behavior 269

to A D instead of the original A B C D, the law of the
resolution of physiological states would be relevant to only a
fraction of learning. For example, let a cat or dog be given
an ordinary discrimination experiment, but so modified
that whether the animal responds by the ‘right’ or the
‘wrong’ act he 1s removed immediately after the reward or
punishment. ‘That is, the event is either S Rr or S Ra,
never S Rr R2. Let the experiment be repeated at inter-
vals so long that the physiological state, St. R1, or St. Ra,
leading to the response Ri or R2 in the last trial, has
ceased before the next. The animal will come to respond to
S by R2 only, though R2 has never been reached by the
‘resolution’ of S Ri Ra.

Cats in jumping for birds or mice, men in playing
billiards, tennis or golf, and many other animals in many
other kinds of behavior, often learn as the dog must in
this experiment. The situation on different occasions is
followed by different responses, but by only one per
occasion. Professor Jennings was misled by treating as
general the special case where the situation itself includes a
condition of discomfort terminable only by a ‘successful’
response or by the animal’s exhaustion or death.

Assuming as typical this same limited case of response
to an annoying situation, so that success consists simply
in replacing the situation by another, Stevenson Smith
reduces the learning-process to the law of exercise alone.
He argues that, —

“For instance, let an organism at birth be capable of
giving N reactions (a, b,c, . . . N) to a definite stimulus
S and let only one of these reactions be appropriate. If
only one reaction can be given at a time and if the one
given is determined by the state of the organism at the
time S is received, there is one chance in N that it is the

270 Animal Intelligence

appropriate reaction. When the appropriate reaction is
finally given, the other reactions are not called into play,
S may cease to act, but until the appropriate reaction is
given let the organism be such that it runs through the
gamut of the others until the appropriate reaction is brought
about. As there are N possible reactions, the chances are
that the appropriate reaction will be given before all N
are performed. At the next appearance of the stimulus,
which we may call S,, those reactions which were in the
last case performed, are, through habit, more likely to be
again brought about than those which were not performed.
Let w stand for the unperformed reactions. Then we have
N —uz probable reactions to S,. Habit rendering the
previously most performed reactions the most probable
throughout we should expect to find the appropriate re-
action in response to

S; contained in N.

S, contained in N — m.

Ss contained in N — uw, — tg.

S, contained in N — nu, which approaches
one as a limit.

Thus the appropriate reaction would be fixed through the
laws of chance and habit. This law of habit is that when
any action is performed a number of times under certain
conditions, it becomes under those conditions more and
more easily performed” (Journal of Comparative Neurology
and Psychology, 1908, Vol. XVIII, pp. 503-504).

This hypothesis is, like Professor Jennings’, adequate to
account for only the one special case, and is adequate to
account for that only upon a further limitation of the number
of times that the animal may repeat any one of his varied
responses to the situation before he has gone through them

Laws and Hypotheses for Behavior 27%

all once, or reached the one that puts an end to the situa-
tion.

The second limitation may be illustrated in the simple
hypothetical case of three responses, 1, 2 and 3, of which
No. 2 is successful. Suppose the animal always to go
through his repertory with xo repetitions until he reaches 2
and so closes the series.

Only the following can happen : —

v2

13/2

2

2

21h OY

2 2
and, in the long run, 2 will happen twice as often as 1 or 3
happens.

Suppose the animal to repeat each response of his reper-
tory six times before changing to another, the remaining
conditions being as above. Then only the following can
happen : —

ji a ae eo ae

ee bbe i 4 3/32)3 3 '2
2

2

Oe We te ben Me Gas ea dhe Be le
SO Sh oo. 23

and in the long run 2 will happen one third as often as 1 or 3
and, though always successful, must, by Smith’s theory,
appear later and later, so that if the animal meets the
situation often enough, he will eventually fail utterly in it!

Animals do, as a matter of fact, commonly repeat responses
many times before changing them,! so that if only the law

? Professor Smith’s own experiments illustrate this.

272 Animal Intelligence

of exercise operated, learning would not be adaptive. Itis
the effect of 2 that gives it the advantage over1 and 3. Of
two responses to the same annoying situation, one continu-
ing and the other relieving it, an animal could never learn
to adopt the latter as a result of the law of exercise alone,
if the former was, originally, twice as likely to occur. 112
would occur as often as 2 and exercise would be equal for
both. The convincing cases are, of course, those where
learning equals the strengthening to supremacy of an
originally very weak connection and the weakening of
originally strong bonds. An animal’s original nature may
lead it to behave as shown below: —

Das ey 'r oO

rig Ge AU ee AE eh a

7s Mas ee we ay. a a ee
and yet the animal’s eventual behavior may be to react to
the situation always by 2. The law of effect is primary,
irreducible to the law of exercise.

THE EVOLUTION OF BEHAVIOR

The acceptance of the laws of exercise and effect as ade-
quate accounts of learning would make notable differences
in the treatment of all problems that concern learning. I
shall take, to illustrate this, the problem of the development
of intellect and character in the animal series, the phylogene-
sis of intellectual and moral behavior.

The difficulties in the way of understanding the evolution
of intellectual and moral behavior have been that neither
what had been evolved nor that from which it had been
evolved was understood.

The behavior of the higher animals, especially man, was
thought to be a product of impulses and ideas which got

Laws and Hypotheses for Behavior 273

into the mind in various ways and had power to arouse
certain acts and other ideas more or less mysteriously, in the
manner described by the laws of ideo-motor action, atten-
tion, association by contiguity, association by similarity,
suggestion, imitation, dynamo-genesis and the like, with
possibly a surplus of acts and ideas due to ‘free will.’ The
mind was treated as a crucible in which a multifarious so-
lution of ideas, impulses and automatisms boiled away,
giving off, as a consequence of a subtle chemistry, an
abundance of thoughts and movements. Human behavior
was rarely viewed from without as a series of responses
bound in various ways to a series of situations. The stu-
dent of animal behavior passed as quickly as might be from
such mere externals to the inner life of the creature, making
it his chief interest to decide whether it had percepts,
memories, concepts, abstractions, ideas of right and wrong,
choices, a self, a conscience, a sense of beauty. The facts
in intellect and character that are due to learning, that are
not the inherited property of the species and that conse-
quently are beyond the scope of evolution in the race,
were not separated off from the facts of original nature.
The comparative psychologist misspent his energy on such
problems as the phylogenesis of the idea of self, moral
judgments, or the sentiment of filial affection.

At the other extreme, the behavior of the protozoa was
elther contemplated in the light of futile analogies, — for
instance, between discriminative reactions and conscious
choice, and between inherited instincts and memory, — or
studied crudely in its results without observation of what
the animals really did. The protozoa were regarded either
as potential ‘conscious selves’ or as drifting lumps turned
hither and thither by the direct effects of light, heat, gravity

and chemical forces upon their tissues.
am

274 Animal Intelligence

The evolution of the intellectual and moral nature which
a higher animal really possesses from the sort of a nature
which the real activities of the protozoa manifest, is far
less difficult to explain.

In so far as the higher animal is a collection of original
tendencies to respond to physical events without and within
the body, subject to modification by the laws of exercise
and effect and by these alone, and in so far as the protozoan
is already possessed of a well-defined repertory of responses
connected with physical events without and within the
body in substantially the manner of the higher animal’s
original tendencies, the problems of the evolution of be-
havior are definite and in the way of solution.

The previous sections gave reason for the belief that the
higher animals, including man, manifest no behavior
beyond expectation from the laws of instinct, exercise and
effect. The human mind was seen to do no more than
connect in accord with original bonds, use and disuse, and
the satisfaction and discomfort resulting to the neurones.
The work of Jennings has shown that the protozoa already
possess full-fledged instincts, homologous with the instincts
of man. They too may have specialized receptors, an
action-system with a well-defined repertory and a connect-
ing system or means of influencing the bonds between the
stimuli received and the motor reactions made. The dif-
ficulties of tracing the possible development of a super-man
from an infra-animal thus disappear.

There is, of course, an abundance of bona fide difficulty
in discovering the unlearned behavior of each group of
animals and in tracing, throughout the animal series,
changes in the physical events to which animals are sensi-
tive so that to each a different response may be attached,
changes in the movements of which animals are capable,

Laws and Hypotheses for Behavior 275

and changes in the bonds by which particular movements
follow particular physical events. To find when and how
animals whose natures remained nearly or quite unchanged
by the satisfying and annoying effects of their behavior,
gave birth to animals that could learn, is perhaps a still
harder task. But these tasks concern problems that are
intelligible matters of fact. They do not require a student
to get out of matter something defined as beyond matter,
or to get volition out of tropisms, or to get ideas of space
and time out of swimming and sleeping.

The evolution of the sensitivities and of the action-
systems of animals has already been subjected to matter-of-
fact study by naturalists. ‘The evolution of the connection-
system will soon be. Each reflex, instinct or capacity,
each bond between a given situation presented to a given
physiological state and a given response, has its an-
cestral tree. Scratching at an irritated spot on the skin
is older than arms. Following an object that is moving
slowly does not have to be explained separately, as a
‘chance’ variation in dogs, sheep and babies. ‘The me-
chanical trades of man are related to the miscellaneous
manipulations of the apes. Little as we know of the con-
nection-systems possessed by animals, we know enough
to be sure that a bond between situation and response
has ancestors and children as truly as does any bodily
organ. Professor Whitman a decade ago showed the pos-
sibility of phylogenetic investigation of instinctive con-
nections in a study which should be a stimulus and model
for many others. In place of any further general account
of the study of the phylogeny of the connection-system,
I shall quote from his account of the concrete phylogeny
of the instinct of incubation.

‘ !

276 Animal Intelligence

“b. The Incubation Instinct

1. Meaning to be Sought in Phyletic Roots. — It seems
quite natural to think of incubation merely as a means of
providing the heat needed for the development of the egg,
and to assume that the need was felt before the means
was found to meet it. Birds and eggs are thus presupposed,
and as the birds could not have foreseen the need, they
could not have hit upon the means except by accident.
Then, what an infinite amount of chancing must have
followed before the first ‘cuddling’ became a habit, and
the habit a perfect instinct! We are driven to such pre-
posterous extremities as the result of taking a purely casual
feature to start with. Incubation supplies the needed heat,
but that is an incidental utility that has nothing to do with
the nature and origin of the instinct. It enables us to see
how natural selection has added some minor adjustments,
but explains nothing more. For the real meaning of the
instinct we must look to its phyletic roots.

If we go back to animals standing near the remote an-
cestors of birds, to the amphibia and fishes, we find the same
instinct stripped of its later disguises. Here one or both
parents simply remain over or near the eggs and keep a
watchful guard against enemies. Sometimes the move-
ments of the parent serve to keep the eggs supplied with
fresh water, but aération is not the purpose for which the
instinct exists.

2. Means Rest and Incidental Protection to Offspring. —
The instinct is a part of the reproductive cycle of activities,
and always holds the same relation in all forms that exhibit
it, whether high or low. It follows the production of eggs,
or young, and means primarily, as I believe, rest, with

Laws and Hypotheses for Behavior 275

incidental protection to offspring. That meaning is always
manifest, no less in worms, molluscs, crustacea, spiders
and insects, than in fishes, amphibia, reptiles and birds.
The instinct makes no distinction between eggs and young,
and that is true all along the line up to birds, which extend
the same blind instinct to one as to the other.

3. Essential Elements of the Instinct. — Every essential
element in the instinct of incubation was present long
before the birds and eggs arrived. These elements are:
(1) the disposition to remain with or over the eggs; (2) the
disposition to resist and drive away enemies; and (3) perio-
dicity. The birds brought all these elements along in
their congenital equipment, and added a few minor adap-
tations, such as cutting the period of incubation to the
need of normal development, and thus avoiding indefinite
waste of time in case of sterile or abortive eggs.

(1) Disposition to Remain over the Eggs. — The disposi-
tion to remain over the eggs is certainly very old, and is
probably bound up with the physiological necessity for rest
after a series of activities tending to exhaust the whole sys-
tem. If this suggestion seems far-fetched, when thinking
of birds, it will seem less so as we go back to simpler con-
ditions, as we find them among some of the lower inverte-
brate forms, which are relatively very inactive and pre-
disposed to remain quiet until impelled by hunger to move.
Here we find animals remaining over their eggs, and thus
shielding them from harm, from sheer inability or indis-
position to move. That is the case with certain molluscs
(Crepidula), the habits and development of which have been
recently studied by Professor Conklin. Here full protec-
tion to offspring is afforded without any exertion on the part
of the parent, in a strictly passive way that excludes even
any instinctive care. In Clepsine there is a manifest un-

278 Animal Intelligence

willingness to leave the eggs, showing that the disposition
to remain over them is instinctive. If we start with forms
of similar sedentary mode of life, it is easy to see that re-
maining over the eggs would be the most likely thing to
happen, even if no instinctive regard for them existed.
The protection afforded would, however, be quite sufficient
to insure the development of the instinct, natural selection
favoring those individuals which kept their position un-
changed long enough for the eggs to hatch.’ !

Professor Whitman proceeds to study the ‘ Disposition
to Resist Enemies’ and the ‘ Periodicity’ in the same genetic
way.

The most important of all original abilities is the ability
to learn. It, like other capacities, has evolved. The
animal series shows a development from animals whose
connection-system suffers little or no permanent modifica-
tion by experience to animals whose connections are in
large measure created by use and disuse, satisfaction and
discomfort.

Some of this development can be explained without re-
course to differences in mere power to learn, by the fact
that the latter animals are given greater stimuli to or re-
wards for learning. But part of it is due to differences in
sheer ability to learn, that is, in the power of equally
satisfying conditions to strengthen or of equally annoying
conditions to weaken bonds in the animals’ connection-
systems. This may be seen from the following simple and
partial case: —

Call 1 and 2 two animals.

Call C, and C, the internal conditions of the two animals

1 Biological Lectures from the Marine Biological Laboratory of Woods
Holl, 1898, p. 323 ff.

Laws and Hypotheses for Behavior 279

except for their connection-systems, each being the aver-
age condition of the animal in question.

Call S; and S, two external states of affairs, each being
near the indifference point for the animal in question, —
that is, being one which the animal does little to either
avoid or secure.

Call G; and G, two responses which result in O, and O, the
optima or most satisfying state of affairs for 1 and 2.

Call I, and I, two responses which result in the continua-
tion of S; and Sg.

The only responses possible for 1 are G, and ],.

The only responses possible for 2 are G, and Iy.

Animal 1 upon the recurrence of S; and C, is little or no
more likely to respond by G, than he was before.

Animal 2 upon the recurrence of S, and Cy is far more
likely to respond by Gg, than he was before.

The fact thus outlined might conceivably be due to an
intrinsic inequality between O, and Og, the power of equally
satisfying optima to influence, their antecedents being iden-
tical. This is not the case in the evolution of learning,
however. For even if, instead of O,, we had only a moder-
ately satisfying state of affairs, such as the company of
other chicks to (2) a 15-day-old chick, while O, was the
optimum of darkness, dampness, coolness, etc., for (1) an
earthworm, 2 would learn far, far more rapidly than 1.

The fact is due, of course, to the unequal power of equally
satisfying conditions to influence their antecedents. The
same argument holds good for the influence of discomfort.

The ability to learn, —that is, the possession of a con-
nection-system subject to the laws of exercise and effect,
—has been found in animals as ‘low’ as the starfish and
perhaps in the protozoa. It is hard to tell whether the
changed responses observed in Stentor by Jennings and in

280 Animal Intelligence

Paramecium by Stevenson Smith are easily forgotten learn-
ings or long retained excitabilities. Sooner or later clear
learning appears, and then, from crabs to fish and turtle,
from these to various birds and mammals, from these to
monkeys, and from these to man, a fairly certain increase
in sheer ability to learn, in the potency of a supposedly
constant degree of satisfyingness or annoyingness to influ-
ence the connection preceding it, can be assumed. We
cannot, of course, define just what we mean by equal satis-
fyingness to a mouse and a man, but the argument Is sub-
stantially the same as that whereby we assume that the
gifted boy has more sheer ability to learn than the idiot, so
that if the two made the same response to the same situa-
tion and were equally satisfied thereby, the former would
form the habit more firmly.

We may, therefore, expect that when knowledge of the
structure and behavior of the neurones comprising the con-
nection-systems of animals (or of the neurones’ predecessors
in this function) progresses far enough to inform us of just
what happens when a connection is made stronger or weaker
and of just what effects satisfying and annoying states of
affairs exert upon the connection-system (and in particular
upon the connections most recently in activity) the ability
to learn will show as true an evolution as the ability to sneeze,
oppose the thumb, or clasp an object touched by the hand.

If my analysis is true, the evolution of behavior is a rather
simple matter. Formally the crab, fish, turtle, dog, cat,
monkey and baby have very similar intellects and charac-
ters. All are systems of connections subject to change by
the law of exercise and effect. The differences are: first, in
the concrete particular connections, in what stimulates the
animal to response, what responses it makes, which stimulus
connects with which response, and second, in the degree of

Laws and Hypotheses for Behavior 281

ability to learn — in the amount of influence of a given de-
gree of satisfyingness or annoyingness upon the connection
that produced it.

The peculiarly human features of intellect and character,
responses to elements and symbols, are the results of:
first, a receiving system that is easily stimulated by the
external world bit by bit (as by focalized vision and touch
with the moving hand) as well as in totals composed of vari-
ous aggregates of these bits; second, of an action-system of
great versatility (as in facial expression, articulation, and
the hands’ movements); and third, of a connection-system
that includes the connections roughly denoted by babbling,
manipulation, curiosity, and satisfaction at activity, bodily
or mental, for its own sake; that is capable of working in
great detail, singling out elements of situations and parts
of responses; and that allows satisfying and annoying states
of affairs to exert great influence on their antecedent con-
nections. Because he learns fast and learns much, in the
animal way, man seems to learn by intuitions of his own.

CHAPTER VII

Tue EvoLutIONnN OF THE HuMAN INTELLEcT!

To the intelligent man with an interest in human nature
it must often appear strange that so much of the energy of
the scientific world has been spent on the study of the body
and so little on the study of the mind. ‘The greatest thing
in man is mind,’ he might say, ‘yet the least studied.’ Es-
pecially remarkable seems the rarity of efforts to trace the
evolution of the human intellect from that of the lower ani-
mals. Since Darwin’s discovery, the beasts of the field,
the fowl of the air and the fish of the sea have been ex-
amined with infinite pains by hundreds of workers in the
effort to trace our physical genealogy, and with consummate
success; yet few and far between have been the efforts to
find the origins of intellect and trace its progress up to hu-
man faculty. And none of them has achieved any secure
SUCCESS.

It may be premature to try again, but a somewhat ex-
tended series of studies of the intelligent behavior of fishes,
reptiles, birds and mammals, including the monkeys, which
it has been my lot to carry out during the last five years, has
brought results which seem to throw light on the problem
and to suggest its solution.

Experiments have been made on fishes, reptiles, birds and
various mammals, notably dogs, cats, mice and monkeys,
to see how they learned to do certain simple things in order

1 This chapter appeared originally in the Popular Science Monthly, Nov.,
IQOT.

282

The Evolution of the Human Intellect 283

to get food. All these animals manifest fundamentally the
same sort of intellectual life. Their learning is after the
same general type. What that type is can be seen best from
a concrete instance. A monkey was kept in a large cage.
Into the cage was put a box, the door of which was held
closed by a wire fastened to a nail which was inserted in a
hole in the top of the box. If the nail was pulled up out of
the hole, the door could be pulled open. In this box was a
piece of banana. The monkey, attracted by the new object,
came down from the top of the cage and fussed over the box.
He pulled at the wire, at the door, and at the bars in the
front of the box. He pushed the box about and tipped it up
and down. He played with the nail and finally pulled it out.
When he happened to pull the door again, of course it opened.
He reached in and got the food inside. It had taken him
36 minutes to get in. Another piece of food being put in
and the door closed, the occurrences of the first trial were
repeated, but there was less of the profitless pulling and tip-
ping. He got in this time in 2 minutes and 20 seconds.
With repeated trials the animal finally came to drop en-
tirely the profitless acts and to take the nail out and open
the door as soon as the box was put in his cage. He had,
we should say, learned to get in.

The process involved in the learning was evidently a
process of selection. The animal is confronted by a state
of affairs or, as we may call it, a ‘situation.’ He reacts in
the way that he is moved by his innate nature or previous
training to do, by a number of acts. These acts include
the particular act that is appropriate and he succeeds. In
later trials the impulse to this one act is more and more
stamped in, this one act is more and more associated with
that situation, is selected from amongst the others by reason
of the pleasure it brings the animal. The profitless acts

284 Animal Intelligence

are stamped out; /the impulses to perform them in that
situation are weakened by reason of the positive discomfort
or the absence of pleasure resulting from them. So the
animal finally performs in that situation only the fitting act.

Here we have the simplest and at the same time the most
widespread sort of intellect or learning in the world. There
is no reasoning, no process of inference or comparison;
there is no thinking about things, no putting two and two
together; there are no ideas — the animal does not think
of the box or of the food or of the act he is to perform. He
simply comes after the learning to feel like doing a certain
thing under certain circumstances which before the learning
he did not feel like doing. Human beings are accustomed
to think of intellect as the power of having and controlling
ideas and of ability to learn as synonymous with ability to
have ideas. But learning by having ideas is really one of
the rare and isolated events in nature. There may be a
few scattered ideas possessed by the higher animals, but the
common form of intelligence with them, their habitual
method of learning, is not by the acquisition of ideas, but
by the selection of impulses.

Indeed this same type of learning isfoundinman. When
we learn to drive a golf ball or play tennis or billiards, when
we learn to tell the price of tea by tasting it or to strike a
certain note exactly with the voice, we do not learn in the
main by virtue of any ideas that are explained to us, by
any inferences that we reason out. We learn by the grad-
ual selection of the appropriate act or judgment, by its
association with the circumstances or situation requiring
it, in just the way that the animals do.

From the lowest animals of which we can affirm intel-
ligence up to man this type of intellect is found. With
it there are in the mammals obscure traces of the ideas

The Evolution of Human Intellect 285

which come in the mental life of man to outweigh and hide it.
But it is the basal fact. As we follow the development
of animals in time, we find the capacity to select impulses
growing. We find the associations thus made between
situation and act growing in number, being formed more
quickly, lasting longer and becoming more complex and
more delicate. The fish can learn to go to certain places, to
take certain paths, to bite at certain things and refuse others,
but not much more. It is an arduous proceeding for him
to learn to get out of a small pen by swimming up through
a hole in a screen. The monkey can learn to do all sorts
of things. It is a comparatively short and easy task for
him to learn to get into a box by unhooking a hook, pushing
a bar around and pulling out a plug. He learns quickly
to climb down to a certain place when he sees a letter T
on a card and to stay still when he sees a K. He performs
the proper acts nearly as well after 50 days as he did when
they were fresh in his mind.

This growth in the number, speed of formation, perma-
nence, delicacy and complexity of associations possible for
an animal reaches its acme in the case of man. Evenif we
leave out of question the power of reasoning, the possession
of a multitude of ideas and abstractions and the power of
control over impulses, purposive action, man is still the
intellectual leader of the animal kingdom by virtue of the
superior development in him of the power of forming as-
sociations between situations or sense-impressions and acts,
by virtue of the degree to which the mere learning by
selection possessed by all intelligent animals has advanced.
In man the type of intellect common to the animal kingdom
finds its fullest development, and with it is combined the
hitherto nonexistent power of thinking about things and
rationally directing action in accord with thought.

286 Animal Intelligence

Indeed it may be that this very reason, self-consciousness
and self-control which seem to sever human intellect so
sharply from that of all other animals are really but second-
ary results of the tremendous increase in the number, deli-
cacy and complexity of associations which the human ani-
mal can form. It may be that the evolution of intellect
has no breaks, that its progress is continuous from its
first appearance to its present condition in adult civilized
human beings. If we could prove that what we call idea-
tional life and reasoning were not new and unexplainable
species of intellectual life but only the natural consequences
of an increase in the number, delicacy, and complexity of
associations of the general animal sort, we should have
made out an evolution of mind comparable to the evolu-
tion of living forms.

In 1890 William James wrote, “‘The more sincerely one
seeks to trace the actual course of psychogenesis, the
steps by which as a race we may have come by the peculiar
mental attributes which we possess, the more clearly one
perceives ‘the slowly gathering twilight close in utter
dark.’”’ Can we perhaps prove him a false prophet? Let
us first see if there be any evidence that makes it probable
that In some way or another the mere extension of the
animal type of intellect has produced the human sort. If
we do, let us proceed to seek a possible account of ow this
might have happened, and finally to examine any evidence
that shows this possible ‘how’ to have been the real way
in which human reason has evolved.

It has already been shown that in the animal kingdom
there is, as we pass from the early vertebrates down to man,
a progress in the evolution of the general associative process
which practically equals animal intellect, that this progress
continues as we pass from the monkeys to man. Such a

The Evolution of Human Intellect 287

progress is a real fact; it does exist as a possible vera causa;
it is thus at all events better than some imaginary cause
of the origin of human intellect, the very existence of
which is in doubt. In a similar manner we know that the
neurones, which compose the brain and the connections
between which are the physiological parallels of the habits
that animals form, show, as we pass down through the
vertebrate series, an evolution along lines of increased deli-
cacy and complexity. That an animal associates a certain
act with a certain felt situation means that he forms or
strengthens connections between certain cells. The in-
crease in number, delicacy and complexity of cell structures
is thus the basis for an increase in the number, delicacy
and complexity of associations. Now the evolution noted
in cell structures affects man as well as the other vertebrates.
He stands at the head of the scale in that respect as well.
May not this obvious supremacy in the animal type of intel-
lect and in the adaption of his brain to it be at the bottom
of his supremacy in being the sole possessor of reasoning ?

This question becomes more pressing if we realize that
we must have some sort of brain correlate for ideational
life and reasoning. Some sort of difference in processes in
the brain must be at the basis of the mental differences be-
tween man and the lower animals, we should all admit. And
it would seem wise to look for that difference amongst differ-
ences which really do or at least may exist. Now the most
likely brain difference between man and the lower animals for
our purpose, to my mind indeed the only likely one, is just this
difference in the fineness of organization of the cell struc-
tures. If we could show with any degree of probability
how it might account for the presence of ideas and of reason-
ing, we should at least have the satisfaction of dealing with
a cause actually known to exist.

288 Animal Intelligence

The next important fact is that the intellect of the infant
six months to a year old is of the animal sort, that ideational
and reasoning life are not present in his case, that the only
obvious intellectual difference between him and a monkey is
in the quantity and quality of the associations formed.
In the evolution of the infant’s mind to its adult condition
we have the actual transition within an individual from the
animal to the human type of intellect. If we look at the
infant and ask what is in him to make in the future a thinker
and reasoner, we must answer either by invoking some myste-
rious capacity, the presence of which we cannot demonstrate,
or by taking the difference we actually do find. That is
the difference in the quality and quantity of associations of
the animal sort. Even if we could never see how it came to
cause the future intellectual life, it would seem wiser to believe
that it did than to resort to faith in mysteries. Surely there
is enough evidence to make it worth while to ask our second
question, ‘‘How might this difference cause the life of ideas
and reasoning ?”’

To answer this question fully would involve a most in-
tricate treatment of the whole intellectual life of man, a
treatment which cannot be attempted without reliance on
technical terms and psychological formulas. A fairly
comprehensible account of the general features of such an
answer can, however, be given. ‘The essential thing about
the thinking of the animals is that they feel things in gross.
The kitten who learned to respond differently to the signals,
“‘T must feed those cats” and ‘‘I will not feed them,” felt
each signal as a vague total, including the tone, the move-
ments of my head, etc. It did not have an idea of the sound
of Z, another of the sound of must, another of the sound
feed, etc. It did not turn the complex impression into a set
of elements, but felt it, as I have said, in gross. The dog

The Evolution of Human Intellect 289

that learned to get out of a box by pulling a loop of wire
did not feel the parts of the box separately, the bolt as a
definite circle of a certain size, did not feel his act as a sum
of certain particular movements. The monkey who learned
to know the letter K from the letter Y did not feel the sepa-
rate lines of the letter, have definite ideas of the parts.
He just felt one way when he saw one total impression and
another way when he saw another.

Strictly human thinking, on the contrary, has as its essen-
tial characteristic the breaking up of gross total situations
into feelings of particular facts. When in the presence
of ten jumping tigers we not only feel like running, but also
feel the number of tigers, their color, their size, etc. When,
instead of merely associating some act with some situation
in the animal way, we think the situation out, we have a
set of particular feelings of its elements. In some cases, it
is true, we remain restricted to the animal sort of feelings.
The sense impressions of suffocation, of the feeling of a
new style of clothes, of the pressure of 10 feet of water above
us, of malaise, of nausea and such like remain for most of us
vague total feelings to which we react and which we feel
most acutely but which do not take the form of definite
ideas that we can isolate or combine or compare. Such
feelings we say are not parts of our real intellectual life.
They are parts of our intellectual life if we mean by it the
mental life concerned in learning, but they are not if we
mean by it the life of reasoning.

Can we now see how the vague gross feelings of the animal
sort might turn into the well-defined particular ideas of the
human sort, by the aid of a multitude of delicate associations ?

It seems to be a general law of mind that any mental
element which occurs with a number of different mental

elements, appears, that is, in a number of different com-
U

290 Animal Intelligence

binations, tends to thereby acquire an independent life
of its own. We show children six lines, six dots, six peas,
six pieces of paper, etc., and thus create the definite feeling
of sixness. Out of the gross feelings of a certain number of
lines, of dots, etc., we evolve the definite elementary feeling
of sixness by making the ‘six’ aspect of the situations
appear in a number of different connections. We learn to
feel whiteness as a definite idea by seeing white paper, white
cloth, white eggs, white plates, etc. We learn to feel
the meaning of but or in or notwithstanding by feeling the
meanings of many total phrases containing each of them.
Now in this general law by which different associates for the
same elementary process elevate it out of its position as
an undifferentiated fragment of a gross total feeling, we
have, I think, the manner in which the vague feelings of
the nine-months-old infant become the definite ideas of
the five-year-old boy, the manner in which in the race
the animal mind has evolved into the human, and the ex-
planation of the service performed by the increase in the
delicacy of structure of the human brain and the conse-
quent increase in the number of associations.

The bottle to the six-months-old infant is a vague sense-
impression which the infant does not think about or indeed
in the common meanings of the words perceive or remem-
ber or imagine. Its presence does not arouse ideas, but
action. It is not to him a thing so big, or so shaped, or
so heavy, but is just a vaguely sizable thing to be reached
for, grabbed and sucked. Like the lower animals, with the
exception that as he grows a little older he reacts in very
many more ways, the child feels things in gross in a way
to lead to direct reactions. Vague sense-impressions and
impulses make up his mental life. The bottle, which to a
dog would be a thing to smell at and paw, to a kitten a

The Evolution of Human Intellect 291

thing to smell at and perhaps worry, is to the child a little
later a thing to grab and suck and turn over and drop and
pick up and pull at and finger and rub against its toes and
so on. The sight of the bottle thus becomes associated
with many different reactions, and thus by our general law
tends to gain a position independent of any of them, to
evolve from the condition of being a portion of the cycles
see-grab, see-drop, see-turn over, etc., to the condition of
being a definite idea.

The increased delicacy and complexity of the cell
structures in the human brain give the possibility of very
small parts of the brain-processes forming different connec-
tions, allow the brain to work in very great detail, provide
processes ready to be turned into definite ideas. The great
number of associations which the human being forms
furnish the means by which this last event is consummated.
The infant’s vague feelings of total situations are by virtue
of the detailed working of his brain all ready to split up
into parts, and his general activity and curiosity provide
the multitude of different connections which allow them to
do so. The dog, on the other hand, has few or no ideas
because his brain acts in coarse fashion and because there
are few connections with each single process.

When once the mind begins to function by having defi-
nite ideas, all the phenomena of reasoning soon appear.
The transition from one idea to another is the feeling of
their relationship, of similarity or difference or whatever
it may be. As soon as we find any words or other symbols
to express such a feeling, or to express our idea of an action
or condition, we have explicit judgments. Observation
of any child will show us that the mind cannot rest in a con-
dition where it has a large body of ideas without comparing
them and thinking about them. The ideas carry within

ne es Pas iy ee

292 Animal Intelligence

them the forces that make abstractions, feelings of simi-
larity, judgments and other characteristics of reason-
ing.

In children two and three years of age we find all these
elements of reasoning present and functioning. The prod-
uct of children’s reasoning is often irrational, but the pro-
cesses are all there. The following instances from a collec-
tion of children’s sayings by Mr. H. W. Brown show children
making inductions and deductions after the same general
fashion as adults : —

(2 yrs.) T. pulled the hairs on his father’s wrist. Father.
“Don’t, T., you hurt papa!” T. “It didn’t hurt grandpa.”

(2 yrs. 5 mos.) M. said, ‘‘ Gracie can’t walk, she wears little
bits of shoes; if she had mine, she could walk. When I getsome
new ones, I’m going to give her these, so she can walk.”

(2 yrs. 9 mos.) He usually has a nap in the forenoon, but
Friday he did not seem sleepy, so his mother did not put him to
bed. Before long he began to say, “ Bolly’s sleepy; mamma put
him in the crib!” This he said very pleasantly at first; but, as
she paid no attention to him, he said, ‘‘ Bolly cry, then mamma
will.” And he sat down on the floor and roared.

(3 yrs.) It was between five and six in the afternoon; the
mother was getting the baby asleep. J. had no one to play with.
He kept saying, “I wish R. would come home; mamma, put
baby to bed, so R. will come home.” I usually get home about
six, and as the baby is put to bed about half-past five, he had
associated the one with the other.

(3 yrs.) W. likes to play with oil paints. Two days ago
my father told W. he must not touch the paints any more, for
he was too small. This morning W. said, “When my papa is a
very old man, and when I am a big man and don’t need any
papa, then I can paint, can’t I, mamma?”

(3 yrs.) G.’s aunt gave him tencents. G. went out, but soon
came back saying, “‘Mamma, we will be rich now.” “Why so,

The Evolution of Human Intellect 293

G.?” “Because I planted my ten cents, and we will have lots of
ten cents growing.”

(3 yrs.) B. climbed up into a large express wagon, and would
not get out. I helped him out, and it was not a minute before
he was back in the wagon. Isaid, “B., how are you going to get
out of therenow?” He replied, “I can stay here till it gets little,
and then I can get out my own self.”

(3 yrs.) F. is not allowed to go to the table to eat unless she
has her face and hands washed and her hair combed. The other
day she went to a lady visiting at her house and said, “Please
wash my face and hands and comb my hair; I am very hungry.”

(3 yrs.) If C. is told not to touch a certain thing, that it will
bite him, he always asks if it has a mouth. The other day he
was examining a plant, to see if it had a mouth. He was told
not to break it, and he said, “‘Oh, it won’t bite, because I can’t
find any mouth.”

Nowhere in the animal kingdom do we find the psycho-
logical elements of reasoning save where there is a mental
life made up of the definite feelings which I have called
‘ideas,’ but they spring up like magic as soon as we get ina
child a body of such ideas. If we have traced satisfactorily
the evolution of a life of ideas from the animal life of vague
sense-impressions and impulses, we may be reasonably sure
that no difficulty awaits us in following the life of ideas
in its course from the chaotic dream of early childhood to
the logical world-view of the adult scientist.

In a very short time we have come a long way, from the
simple learning of the minnow or chick to the science and
logicofman. The general frame of mind which one acquires
from the study of animal behavior and of the mental de-
velopment of young children makes our hypothesis seem
vital and probable. If the facts did eventually corroborate
it, we should have an eminently simple genesis of human

204 Animal Intelligence

faculty, for we could put together the gist of our contention
in a few words. We should say : —

“The function of intellect is to provide a means of modi-
fying our reactions to the circumstances of life, so that we
may secure pleasure, the symptom of welfare. Its general
law is that when in a certain situation an animal acts so
that pleasure results, that act is selected from all those per-
formed and associated with that situation, so that, when
the situation recurs, the act will be more likely to follow than
it was before; that on the contrary the acts which, when
performed in a certain situation, have brought discomfort,
tend to be dissociated from that situation. The intellectual
evolution of the race consists in an increase in the number,
delicacy, complexity, permanence and speed of formation
of such associations. In man this increase reaches such a
point that an apparently new type of mind results, which
conceals the real continuity of the process. This mental
evolution parallels the evolution of the cell structures of
the brain from few and simple and gross to many and
complex and delicate.”’

Nowhere more truly than in his mental capacities is man
apart ofnature. His instincts, that is, his inborn tendencies
to feel and act in certain ways, show throughout marks of
kinship with the lower animals, especially with our nearest
relatives physically, the monkeys. His sense-powers show
no new creation. His intellect we have seen to be a
simple though extended variation from the general animal
sort. This again is presaged by the similar variation
in the case of the monkeys. Amongst the minds of animals
that of man leads, not as a demigod from another planet,
but as a king from the same race.

INDEX

Abstraction, 120. See also Reasoning.
Action-system, importance of the study
of the, 15 f.; of monkeys, 190 f., 237.

Anecdotal school in animal psychology,

agi. cea, t:

Apparatus, descriptions of, 29 ff., 56 ff.,
6r:f;, 160 f., 177 ff.,.106 ff.

Assimilation, 2409 f.

Association, as a problem in animal psy-
chology, 20 ff.; by similarity, 116 ff.;
complexity of, 132 ff.; conditions of,
43 ff.; delicacy of, 128 ff., 195 ff. ; de-
velopment of, in the animal kingdom,
285 ff.; in cats, 38 ff.; in chicks, 63 f.;
in dogs, 56 ff.; in fishes, 169 ff.; in
man, 123 ff., 127, 285; in monkeys,
182 fi., 194 f.; 209 ff.; in relation to
attention, 44 ff.; to individual differ-
ences, 52 ff.; to inhibition, 142 ff.; to
instincts, 36 f., 142 ff.; to previous ex-
perience, 48 ff.; number of connections
formed by, 135 ff.; permanence of con-
nections formed by, 138 ff., 194 f., 203
f.; progress of, measurable by time-
curves, 28, 40, 42; the mental fact in,
08 ff.; without ideas, ror f., 127, 200 ff.
See also Associations and Learning.

Associations, complexity, 132 ff.; deli-
cacy, 128 ff., 195 ff.; number, 121,
135 ff.; permanence, 138 ff., 194 f.,
203 f.

Associative memory. See Association.

Attention, 144 ff.; and association, 44 ff. ;
to imposed movements, 103 ff.

Behavior, acquired tendencies to, 244 ff.
(see also Association); evolution of,
272 ff.; general laws of, 241 ff.; in-
definiteness of the term, 5; of cats,
35 ff., 88 f., and passim; of chicks, 63 f.,
138, 143 f., 156 ff., and passim; of dogs,
59 ff., 92 ff.; of fishes, 169 ff.; of
monkeys, 182 ff.; original tendencies
to, 242 f. (see also Instincts); pre-
dictability of, 241 f.; proposed sim-
plification of the laws of, 265 ff.;

versus consciousness as an object of

study, 1 ff. See also Association,

Instincts, Learning, Memory, etc.
BoswortH, F. D., 240.

Cats, associative processes in, 35 ff.;
imitation in, 85 ff.; the presence of
ideas in, 100 ff.; reasoning in, 67 ff.

Chicks, associative processes in, 61 ff.;
imitation in, 81 ff.; instincts of, 156 ff.

Complexity, of associations, 132 ff.

Concepts, 116 ff.

Connection-systems, action of, in asso-
ciation, 246 ff., 266; importance of
the study of, 16 f.

Consciousness, amenability of, to scien-
tific study, 7 ff.; as pure experience,
13 f.; as studied by the one who has
or is it, 10 ff.; of animals, 25 f., 67 ff.,
08 ff., 123, 146 f., and passim; social,
146 f.; space-relations of, 14; versus
behavior as an object of study, 1 ff.

Codrdinations, of chicks, 160 ff.

Dean, B., 161.

Delicacy of association, 128 ff., 195 ff.

DEWEY, J., 6.

Differences, between species of animals
in the associative processes, 64 ff.

Discomfort, as an influence in learning,
245 fi.

Discrimination, in cats and dogs, 128 ff.;
in chicks, 156 ff.; in monkeys, 105 ff.

Dogs, associative processes in, 56 ff.;
imitation in, gr ff.; the presence of
ideas in, 115 f.; reasoning in, 67 ff.

Education, applications of animal psy-
chology in, 149 f.

Effect, the law of, 244 f., 266 ff.

Emotional reactions of chicks, 162 ff.

Evolution, of behavior, 272 ff.; of human
intellect, 282 ff.; of ideas, 289 ff.

Exercise, the law of, 244 f.

Experience, the influence of previous,
48 ff.

295

296

Experiments, need of, in animal psy-
chology, 26; with cats, 35 ff., 85 ff.,
104 ft. TEL ts SEA 1420 Ms, Ego Aes
with chicks, 61 ff., ‘81 fi., 132, 136,
143 f., 156 ff.; with dogs, 56 ff., o1 ff.,
103 ff., 115 f.; with fishes, 169 ff.;
with monkeys, 176-235, passim.

Fears, of chicks, 162 ff.
Fishes, experiments with, 169 ff.

GALTON, F., 3.

Habit. See Association.
HALE GG: S., 3.
Human. See Man.

Hunger, effect of, on animal learning,
27 f.
Hunt, H. E., 163.

Ideas, development of, 121 f., 289 fi.;
existence of, as adjuncts in animal
learning, 108 ff., 189 ff., 206 ff., 222 ff.;
impotence of, to create connections,
257 fi.

Ideo-motor action, 257 ff.

Images, 108 f. See also Ideas.

Imitation, analysis of the supposed efiects
of, 251 ff.; in cats, 85 ff.; in chicks,
81 ff.; in dogs, o1 ff.; in general, 76 ff.,
94 ff.; in monkeys, 96, 211 ff., 2109 ff.;
in speech, 253 ff.

Impulses, as features of the associative
processes, 100 ff.; defined, 37.

Incubation, the instinct of, 276 ff.

Individual differences in association, 52 ff.

Inhibition of instincts by association,
142 ff.

Instincts, as explanations of some cases
of supposed imitation, 251; inhibition
of, 142 ff.; of chicks, 156 ff.; of in-
cubation, 276 ff.; of monkeys, 237;
the starting-point of animal learning,
36 f.

Intellect. See Association, Ideas, Imita-
tion, Memory, Reasoning, etc.

Interaction, 147 f.

Introspection, the over-emphasis of, 3.

JAMES, W., 3, 120, 143, 286.
JENNINGS, H. S., 267, 268, 260, 270, 274,
270.

Kung, L. W., 173.

Index

Language, 253 ff.

Learning, evolution of, 278 ff.; methods
of, 174 f. See Association, Behavior,
Ideas, Imitation, Reasoning.

LuBBOCK, J., 240.

Man, compared with lower animals in
intellect, 123 ff., 239 f.; mental evolu-
tion of, 282 ff.

Memory, 108 f., 138 ff., 203. See Asso-
ciation and Permanence of associa-
tions.

Methods in animal psychology, 22 ff.

Mitts, W., tor.

Monkeys, 172 ff.; associative processes
in, 182 ff.; differences from lower
mammals, 189 ff., 204 ff., 237 ff.;
general mental development of, 236 ff.;
imitation of man by, 211 ff.; imitation
of other monkeys by, 219 ff.; possible
mental degeneracy of, 151; presence
of ideas in, 189 ff., 206 ff., 222 ff.;
reasoning in, 184 ff.

Moreay, C. L., 3, 80, 99 f., 101, 119, 120,
125 f., 146, 147, 162, 165 f.

Motives, used in the experiments, 26 ff.;
defined, 38.

Number of associations, 135 ff. ; as a cause
of the development of free ideas, 121 f.

PEckHaM, G. W. and E. G., 240.

Pecking, accuracy of, in chicks, 159 f.

Pedagogy, applications of animal psy-
chology to, 149 f.

Permanence of associations, 138 ff., 203.

Predictability of behavior, 241 f.

Primates. See Monkeys.

Reasoning, 118 f.; and free ideas, 291 ff.;
as a consequence of the laws of exer-
cise and effect, 263 ff.; in cats and
dogs, 67 ff.; in monkeys, 184 ff.

Recepts, 120.

Resolution, Jennings’ law of, 267 ff.

Responses to situations as the general
form of behavior, 242 ff., 283 f.

RoMANES, G. J., 68 f., 70, 80.

SANTAYANA, G., 6, 18 f.

Satisfaction, the influence of, in learning,
147 f., 244 f.; the nature of, 245 f.

Situation and response as the general
form of behavior, 242 ff., 283 ff.

Index 297

Sma, W. S., 173. Time-curves, 38 ff., 57 ff., 65, 185 f.; as
SMITH, S., 269 f., 280. evidence against the existence of
Social consciousness of animals, 146 f. reasoning, 73 f.

SPALDING, D. A., 162, 163, 165. TITCHENER, E. B., 2.

Stout, G. F., 3.

Swimming, by chicks, 161 f. Vigor, as a factor in learning, 46.

Time of achievement as a measure of | Wurrman, C. O., 275 ff.
the closeness of association, 28, 40, 42,
54. YERKES, R. M., 240.

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